refactor(nuxt): enable strict type checking (#6368)

Co-authored-by: Pooya Parsa <pooya@pi0.io>

packages/kit/src/loader/config.ts

@@ -7,7 +7,7 @@ import { NuxtConfigSchema } from '@nuxt/schema'
 export interface LoadNuxtConfigOptions extends LoadConfigOptions<NuxtConfig> {}
 
 export async function loadNuxtConfig (opts: LoadNuxtConfigOptions): Promise<NuxtOptions> {
-  const { config: nuxtConfig, configFile, layers, cwd } = await loadConfig({
+  const { config: nuxtConfig, configFile, layers, cwd } = await loadConfig<NuxtConfig>({
     name: 'nuxt',
     configFile: 'nuxt.config',
     rcFile: '.nuxtrc',
@@ -23,6 +23,7 @@ export async function loadNuxtConfig (opts: LoadNuxtConfigOptions): Promise<Nuxt
 
   // Resolve `rootDir` & `srcDir` of layers
   for (const layer of layers) {
+    layer.config = layer.config || {}
     layer.config.rootDir = layer.config.rootDir ?? layer.cwd
     layer.config.srcDir = resolve(layer.config.rootDir, layer.config.srcDir)
   }

packages/nuxt/src/app/compat/capi.ts

@@ -2,19 +2,19 @@ export * from 'vue'
 
 export const install = () => {}
 
-export function set (target, key, val) {
+export function set (target: any, key: string | number | symbol, val: any) {
   if (Array.isArray(target)) {
-    target.length = Math.max(target.length, key)
+    target.length = Math.max(target.length, key as number)
-    target.splice(key, 1, val)
+    target.splice(key as number, 1, val)
     return val
   }
   target[key] = val
   return val
 }
 
-export function del (target, key) {
+export function del (target: any, key: string | number | symbol) {
   if (Array.isArray(target)) {
-    target.splice(key, 1)
+    target.splice(key as number, 1)
     return
   }
   delete target[key]

packages/nuxt/src/app/components/nuxt-error-boundary.ts

@@ -8,7 +8,7 @@ export default defineComponent({
     }
   },
   setup (_props, { slots, emit }) {
-    const error = ref(null)
+    const error = ref<Error | null>(null)
     const nuxtApp = useNuxtApp()
 
     onErrorCaptured((err) => {

packages/nuxt/src/app/components/nuxt-link.ts

@@ -1,10 +1,10 @@
-import { defineComponent, h, resolveComponent, PropType, computed, DefineComponent } from 'vue'
+import { defineComponent, h, resolveComponent, PropType, computed, DefineComponent, ComputedRef } from 'vue'
-import { RouteLocationRaw, Router } from 'vue-router'
+import { RouteLocationRaw } from 'vue-router'
 import { hasProtocol } from 'ufo'
 
 import { navigateTo, useRouter } from '#app'
 
-const firstNonUndefined = <T>(...args: T[]): T => args.find(arg => arg !== undefined)
+const firstNonUndefined = <T>(...args: (T | undefined)[]) => args.find(arg => arg !== undefined)
 
 const DEFAULT_EXTERNAL_REL_ATTRIBUTE = 'noopener noreferrer'
 
@@ -24,8 +24,8 @@ export type NuxtLinkProps = {
   custom?: boolean
 
   // Attributes
-  target?: string
+  target?: string | null
-  rel?: string
+  rel?: string | null
   noRel?: boolean
 
   // Styling
@@ -39,7 +39,7 @@ export type NuxtLinkProps = {
 export function defineNuxtLink (options: NuxtLinkOptions) {
   const componentName = options.componentName || 'NuxtLink'
 
-  const checkPropConflicts = (props: NuxtLinkProps, main: string, sub: string): void => {
+  const checkPropConflicts = (props: NuxtLinkProps, main: keyof NuxtLinkProps, sub: keyof NuxtLinkProps): void => {
     if (process.dev && props[main] !== undefined && props[sub] !== undefined) {
       console.warn(`[${componentName}] \`${main}\` and \`${sub}\` cannot be used together. \`${sub}\` will be ignored.`)
     }
@@ -116,10 +116,10 @@ export function defineNuxtLink (options: NuxtLinkOptions) {
       }
     },
     setup (props, { slots }) {
-      const router = useRouter() as Router | undefined
+      const router = useRouter()
 
       // Resolving `to` value from `to` and `href` props
-      const to = computed<string | RouteLocationRaw>(() => {
+      const to: ComputedRef<string | RouteLocationRaw> = computed(() => {
         checkPropConflicts(props, 'to', 'href')
 
         return props.to || props.href || '' // Defaults to empty string (won't render any `href` attribute)
@@ -127,7 +127,7 @@ export function defineNuxtLink (options: NuxtLinkOptions) {
 
       // Resolving link type
       const isExternal = computed<boolean>(() => {
-        // External prop is explictly set
+        // External prop is explicitly set
         if (props.external) {
           return true
         }
@@ -180,11 +180,13 @@ export function defineNuxtLink (options: NuxtLinkOptions) {
 
         // https://router.vuejs.org/api/#custom
         if (props.custom) {
-          if (!slots.default) { return null }
+          if (!slots.default) {
+            return null
+          }
           return slots.default({
             href,
             navigate,
-            route: router.resolve(href),
+            route: router.resolve(href!),
             rel,
             target,
             isActive: false,

packages/nuxt/src/app/components/utils.ts

@@ -1,11 +1,11 @@
-import { h } from 'vue'
+import { defineComponent, h } from 'vue'
 import type { Component } from 'vue'
 
-const Fragment = {
+const Fragment = defineComponent({
   setup (_props, { slots }) {
     return () => slots.default?.()
   }
-}
+})
 
 /**
  * Internal utility

packages/nuxt/src/app/composables/asyncData.ts

@@ -1,6 +1,5 @@
 import { onBeforeMount, onServerPrefetch, onUnmounted, ref, getCurrentInstance, watch, unref } from 'vue'
 import type { Ref, WatchSource } from 'vue'
-import { wrapInRef } from './utils'
 import { NuxtApp, useNuxtApp } from '#app'
 
 export type _Transform<Input = any, Output = any> = (input: Input) => Output
@@ -25,7 +24,7 @@ export interface AsyncDataOptions<
   > {
   server?: boolean
   lazy?: boolean
-  default?: () => DataT | Ref<DataT>
+  default?: () => DataT | Ref<DataT> | null
   transform?: Transform
   pick?: PickKeys
   watch?: MultiWatchSources
@@ -37,10 +36,10 @@ export interface RefreshOptions {
 }
 
 export interface _AsyncData<DataT, ErrorT> {
-  data: Ref<DataT>
+  data: Ref<DataT | null>
   pending: Ref<boolean>
   refresh: (opts?: RefreshOptions) => Promise<void>
-  error: Ref<ErrorT>
+  error: Ref<ErrorT | null>
 }
 
 export type AsyncData<Data, Error> = _AsyncData<Data, Error> & Promise<_AsyncData<Data, Error>>
@@ -70,7 +69,7 @@ export function useAsyncData<
   DataE = Error,
   Transform extends _Transform<DataT> = _Transform<DataT, DataT>,
   PickKeys extends KeyOfRes<Transform> = KeyOfRes<Transform>
-> (...args): AsyncData<PickFrom<ReturnType<Transform>, PickKeys>, DataE | null | true> {
+> (...args: any[]): AsyncData<PickFrom<ReturnType<Transform>, PickKeys>, DataE | null | true> {
   const autoKey = typeof args[args.length - 1] === 'string' ? args.pop() : undefined
   if (typeof args[0] !== 'string') { args.unshift(autoKey) }
 
@@ -102,7 +101,8 @@ export function useAsyncData<
   // Setup hook callbacks once per instance
   const instance = getCurrentInstance()
   if (instance && !instance._nuxtOnBeforeMountCbs) {
-    const cbs = instance._nuxtOnBeforeMountCbs = []
+    instance._nuxtOnBeforeMountCbs = []
+    const cbs = instance._nuxtOnBeforeMountCbs
     if (instance && process.client) {
       onBeforeMount(() => {
         cbs.forEach((cb) => { cb() })
@@ -115,7 +115,7 @@ export function useAsyncData<
   const useInitialCache = () => options.initialCache && nuxt.payload.data[key] !== undefined
 
   const asyncData = {
-    data: wrapInRef(nuxt.payload.data[key] ?? options.default()),
+    data: ref(nuxt.payload.data[key] ?? options.default?.() ?? null),
     pending: ref(!useInitialCache()),
     error: ref(nuxt.payload._errors[key] ?? null)
   } as AsyncData<DataT, DataE>
@@ -151,7 +151,7 @@ export function useAsyncData<
       })
       .catch((error: any) => {
         asyncData.error.value = error
-        asyncData.data.value = unref(options.default())
+        asyncData.data.value = unref(options.default?.() ?? null)
       })
       .finally(() => {
         asyncData.pending.value = false
@@ -230,7 +230,7 @@ export function useLazyAsyncData<
   DataE = Error,
   Transform extends _Transform<DataT> = _Transform<DataT, DataT>,
   PickKeys extends KeyOfRes<Transform> = KeyOfRes<Transform>
-> (...args): AsyncData<PickFrom<ReturnType<Transform>, PickKeys>, DataE | null | true> {
+> (...args: any[]): AsyncData<PickFrom<ReturnType<Transform>, PickKeys>, DataE | null | true> {
   const autoKey = typeof args[args.length - 1] === 'string' ? args.pop() : undefined
   if (typeof args[0] !== 'string') { args.unshift(autoKey) }
   const [key, handler, options] = args as [string, (ctx?: NuxtApp) => Promise<DataT>, AsyncDataOptions<DataT, Transform, PickKeys>]
@@ -249,7 +249,7 @@ export function refreshNuxtData (keys?: string | string[]): Promise<void> {
 function pick (obj: Record<string, any>, keys: string[]) {
   const newObj = {}
   for (const key of keys) {
-    newObj[key] = obj[key]
+    (newObj as any)[key] = obj[key]
   }
   return newObj
 }

packages/nuxt/src/app/composables/component.ts

@@ -9,8 +9,8 @@ export const NuxtComponentIndicator = '__nuxt_component'
 async function runLegacyAsyncData (res: Record<string, any> | Promise<Record<string, any>>, fn: (nuxtApp: NuxtApp) => Promise<Record<string, any>>) {
   const nuxt = useNuxtApp()
   const route = useRoute()
-  const vm = getCurrentInstance()
+  const vm = getCurrentInstance()!
-  const { fetchKey } = vm.proxy.$options
+  const { fetchKey } = vm.proxy!.$options
   const key = typeof fetchKey === 'function' ? fetchKey(() => '') : fetchKey || route.fullPath
   const { data } = await useAsyncData(`options:asyncdata:${key}`, () => fn(nuxt))
   if (data.value && typeof data.value === 'object') {
@@ -38,8 +38,7 @@ export const defineNuxtComponent: typeof defineComponent =
       setup (props, ctx) {
         const res = setup?.(props, ctx) || {}
 
-        let promises: unknown[] | undefined = []
+        const promises: Promise<any>[] = []
-        promises = promises || []
         if (options.asyncData) {
           promises.push(runLegacyAsyncData(res, options.asyncData))
         }
@@ -49,7 +48,6 @@ export const defineNuxtComponent: typeof defineComponent =
           .then(() => res)
           .finally(() => {
             promises.length = 0
-            promises = null
           })
       }
     } as DefineComponent

packages/nuxt/src/app/composables/cookie.ts

@@ -1,11 +1,10 @@
-import { Ref, watch } from 'vue'
+import { ref, Ref, watch } from 'vue'
 import { parse, serialize, CookieParseOptions, CookieSerializeOptions } from 'cookie-es'
 import { appendHeader } from 'h3'
 import type { CompatibilityEvent } from 'h3'
 import destr from 'destr'
 import { isEqual } from 'ohash'
 import { useRequestEvent } from './ssr'
-import { wrapInRef } from './utils'
 import { useNuxtApp } from '#app'
 
 type _CookieOptions = Omit<CookieSerializeOptions & CookieParseOptions, 'decode' | 'encode'>
@@ -26,9 +25,9 @@ const CookieDefaults: CookieOptions<any> = {
 
 export function useCookie <T = string> (name: string, _opts?: CookieOptions<T>): CookieRef<T> {
   const opts = { ...CookieDefaults, ..._opts }
-  const cookies = readRawCookies(opts)
+  const cookies = readRawCookies(opts) || {}
 
-  const cookie = wrapInRef<T>(cookies[name] ?? opts.default?.())
+  const cookie = ref<T | undefined>(cookies[name] as any ?? opts.default?.())
 
   if (process.client) {
     watch(cookie, () => { writeClientCookie(name, cookie.value, opts as CookieSerializeOptions) })
@@ -46,7 +45,7 @@ export function useCookie <T=string> (name: string, _opts?: CookieOptions<T>): C
   return cookie as CookieRef<T>
 }
 
-function readRawCookies (opts: CookieOptions = {}): Record<string, string> {
+function readRawCookies (opts: CookieOptions = {}): Record<string, string> | undefined {
   if (process.server) {
     return parse(useRequestEvent()?.req.headers.cookie || '', opts)
   } else if (process.client) {

packages/nuxt/src/app/composables/fetch.ts

@@ -37,7 +37,7 @@ export function useFetch<
   arg1?: string | UseFetchOptions<_ResT, Transform, PickKeys>,
   arg2?: string
 ) {
-  const [opts, autoKey] = typeof arg1 === 'string' ? [{}, arg1] : [arg1, arg2]
+  const [opts = {}, autoKey] = typeof arg1 === 'string' ? [{}, arg1] : [arg1, arg2]
   const _key = opts.key || autoKey
   if (!_key || typeof _key !== 'string') {
     throw new TypeError('[nuxt] [useFetch] key must be a string: ' + _key)

packages/nuxt/src/app/composables/router.ts

@@ -61,7 +61,7 @@ export interface NavigateToOptions {
   redirectCode?: number
 }
 
-export const navigateTo = (to: RouteLocationRaw, options: NavigateToOptions = {}): Promise<void | NavigationFailure> | RouteLocationRaw => {
+export const navigateTo = (to: RouteLocationRaw | undefined | null, options: NavigateToOptions = {}): Promise<void | NavigationFailure> | RouteLocationRaw => {
   if (!to) {
     to = '/'
   }
@@ -74,7 +74,7 @@ export const navigateTo = (to: RouteLocationRaw, options: NavigateToOptions = {}
     const nuxtApp = useNuxtApp()
     if (nuxtApp.ssrContext && nuxtApp.ssrContext.event) {
       const redirectLocation = joinURL(useRuntimeConfig().app.baseURL, router.resolve(to).fullPath || '/')
-      return nuxtApp.callHook('app:redirected').then(() => sendRedirect(nuxtApp.ssrContext.event, redirectLocation, options.redirectCode || 302))
+      return nuxtApp.callHook('app:redirected').then(() => sendRedirect(nuxtApp.ssrContext!.event, redirectLocation, options.redirectCode || 302))
     }
   }
   // Client-side redirection using vue-router

packages/nuxt/src/app/composables/ssr.ts

@@ -5,9 +5,9 @@ import { NuxtApp } from '#app/nuxt'
 
 export function useRequestHeaders<K extends string = string> (include: K[]): Record<K, string | undefined>
 export function useRequestHeaders (): Readonly<Record<string, string | undefined>>
-export function useRequestHeaders (include?) {
+export function useRequestHeaders (include?: any[]) {
   if (process.client) { return {} }
-  const headers: Record<string, string | string[]> = useNuxtApp().ssrContext?.event.req.headers ?? {}
+  const headers = useNuxtApp().ssrContext?.event.req.headers ?? {}
   if (!include) { return headers }
   return Object.fromEntries(include.filter(key => headers[key]).map(key => [key, headers[key]]))
 }

packages/nuxt/src/app/composables/state.ts

@@ -10,7 +10,7 @@ import { useNuxtApp } from '#app'
  */
 export function useState <T> (key?: string, init?: (() => T | Ref<T>)): Ref<T>
 export function useState <T> (init?: (() => T | Ref<T>)): Ref<T>
-export function useState <T> (...args): Ref<T> {
+export function useState <T> (...args: any): Ref<T> {
   const autoKey = typeof args[args.length - 1] === 'string' ? args.pop() : undefined
   if (typeof args[0] !== 'string') { args.unshift(autoKey) }
   const [_key, init] = args as [string, (() => T | Ref<T>)]

packages/nuxt/src/app/composables/utils.ts

@@ -1,3 +0,0 @@
-import { isRef, ref, Ref } from 'vue'
-
-export const wrapInRef = <T> (value: T | Ref<T>) => isRef(value) ? value : ref(value)

packages/nuxt/src/app/entry.ts

@@ -35,7 +35,7 @@ if (process.server) {
       await nuxt.hooks.callHook('app:created', vueApp)
     } catch (err) {
       await nuxt.callHook('app:error', err)
-      nuxt.payload.error = nuxt.payload.error || err
+      nuxt.payload.error = (nuxt.payload.error || err) as any
     }
 
     return vueApp
@@ -66,7 +66,7 @@ if (process.client) {
       await applyPlugins(nuxt, plugins)
     } catch (err) {
       await nuxt.callHook('app:error', err)
-      nuxt.payload.error = nuxt.payload.error || err
+      nuxt.payload.error = (nuxt.payload.error || err) as any
     }
 
     try {
@@ -77,11 +77,11 @@ if (process.client) {
       await nextTick()
     } catch (err) {
       await nuxt.callHook('app:error', err)
-      nuxt.payload.error = nuxt.payload.error || err
+      nuxt.payload.error = (nuxt.payload.error || err) as any
     }
   }
 
-  entry().catch((error) => {
+  entry().catch((error: unknown) => {
     console.error('Error while mounting app:', error) // eslint-disable-line no-console
   })
 }

packages/nuxt/src/app/nuxt.ts

@@ -38,19 +38,7 @@ export interface RuntimeNuxtHooks {
   'vue:error': (...args: Parameters<Parameters<typeof onErrorCaptured>[0]>) => HookResult
 }
 
-interface _NuxtApp {
+export interface NuxtSSRContext extends SSRContext {
-  vueApp: App<Element>
-  globalName: string
-
-  hooks: Hookable<RuntimeNuxtHooks>
-  hook: _NuxtApp['hooks']['hook']
-  callHook: _NuxtApp['hooks']['callHook']
-
-  [key: string]: any
-
-  _asyncDataPromises?: Record<string, Promise<any>>
-
-  ssrContext?: SSRContext & {
   url: string
   event: CompatibilityEvent
   /** @deprecated Use `event` instead. */
@@ -66,10 +54,24 @@ interface _NuxtApp {
   teleports?: Record<string, string>
   renderMeta?: () => Promise<NuxtMeta> | NuxtMeta
 }
+
+interface _NuxtApp {
+  vueApp: App<Element>
+  globalName: string
+
+  hooks: Hookable<RuntimeNuxtHooks>
+  hook: _NuxtApp['hooks']['hook']
+  callHook: _NuxtApp['hooks']['callHook']
+
+  [key: string]: any
+
+  _asyncDataPromises: Record<string, Promise<any> | undefined>
+
+  ssrContext?: NuxtSSRContext
   payload: {
     serverRendered?: boolean
-    data?: Record<string, any>
+    data: Record<string, any>
-    state?: Record<string, any>
+    state: Record<string, any>
     rendered?: Function
     error?: Error | {
       url: string
@@ -135,24 +137,24 @@ export function createNuxtApp (options: CreateOptions) {
     }
     // Expose to server renderer to create window.__NUXT__
     nuxtApp.ssrContext = nuxtApp.ssrContext || {} as any
-    if (nuxtApp.ssrContext.payload) {
+    if (nuxtApp.ssrContext!.payload) {
-      Object.assign(nuxtApp.payload, nuxtApp.ssrContext.payload)
+      Object.assign(nuxtApp.payload, nuxtApp.ssrContext!.payload)
     }
-    nuxtApp.ssrContext.payload = nuxtApp.payload
+    nuxtApp.ssrContext!.payload = nuxtApp.payload
 
     // Expose client runtime-config to the payload
     nuxtApp.payload.config = {
-      public: options.ssrContext.runtimeConfig.public,
+      public: options.ssrContext!.runtimeConfig.public,
-      app: options.ssrContext.runtimeConfig.app
+      app: options.ssrContext!.runtimeConfig.app
     }
   }
 
   // Expose runtime config
   const runtimeConfig = process.server
-    ? options.ssrContext.runtimeConfig
+    ? options.ssrContext!.runtimeConfig
     : reactive(nuxtApp.payload.config)
 
-  // Backward compatibilty following #4254
+  // Backward compatibility following #4254
   const compatibilityConfig = new Proxy(runtimeConfig, {
     get (target, prop) {
       if (prop === 'public') {
@@ -192,9 +194,9 @@ export async function applyPlugins (nuxtApp: NuxtApp, plugins: Plugin[]) {
 }
 
 export function normalizePlugins (_plugins: Plugin[]) {
-  const unwrappedPlugins = []
+  const unwrappedPlugins: Plugin[] = []
-  const legacyInjectPlugins = []
+  const legacyInjectPlugins: Plugin[] = []
-  const invalidPlugins = []
+  const invalidPlugins: Plugin[] = []
 
   const plugins = _plugins.map((plugin) => {
     if (typeof plugin !== 'function') {

packages/nuxt/src/app/plugins/logs.client.dev.ts

@@ -6,7 +6,7 @@ export default defineNuxtPlugin((nuxtApp) => {
   if (logs.length > 0) {
     const ssrLogStyle = 'background: #003C3C;border-radius: 0.5em;color: white;font-weight: bold;padding: 2px 0.5em;'
     console.groupCollapsed && console.groupCollapsed('%cNuxt Server Logs', ssrLogStyle)
-    logs.forEach(logObj => (console[logObj.type] || console.log)(...logObj.args))
+    logs.forEach((logObj:any) => (console[logObj.type as 'log'] || console.log)(...logObj.args))
     delete nuxtApp.payload.logs
     console.groupEnd && console.groupEnd()
   }

packages/nuxt/src/app/plugins/progress.client.ts

@@ -13,8 +13,8 @@ export default defineNuxtPlugin((nuxtApp) => {
     el.style.transition = 'width 0.1s, opacity 0.4s'
     const duration = 3000
     const progress = 10000 / Math.floor(duration)
-    let timeout
+    let timeout: ReturnType<typeof setTimeout> | undefined
-    let interval
+    let interval: ReturnType<typeof setInterval> | undefined
     nuxtApp.hook('page:start', () => {
       if (timeout) { return }
       timeout = setTimeout(() => {
@@ -30,9 +30,9 @@ export default defineNuxtPlugin((nuxtApp) => {
     })
     nuxtApp.hook('page:finish', () => {
       timeout && clearTimeout(timeout)
-      timeout = null
+      timeout = undefined
       interval && clearInterval(interval)
-      interval = null
+      interval = undefined
       el.style.width = '100%'
       el.style.opacity = '0%'
       setTimeout(() => {

packages/nuxt/src/app/plugins/router.ts

@@ -1,9 +1,8 @@
 import { reactive, h } from 'vue'
 import { parseURL, parseQuery, withoutBase, isEqual, joinURL } from 'ufo'
 import { createError } from 'h3'
-import { defineNuxtPlugin } from '..'
+import { defineNuxtPlugin, clearError, navigateTo, showError, useRuntimeConfig } from '..'
 import { callWithNuxt } from '../nuxt'
-import { clearError, navigateTo, showError, useRuntimeConfig } from '#app'
 // @ts-ignore
 import { globalMiddleware } from '#build/middleware'
 
@@ -90,8 +89,9 @@ interface Router {
 export default defineNuxtPlugin<{ route: Route, router: Router }>((nuxtApp) => {
   const initialURL = process.client
     ? withoutBase(window.location.pathname, useRuntimeConfig().app.baseURL) + window.location.search + window.location.hash
-    : nuxtApp.ssrContext.url
+    : nuxtApp.ssrContext!.url
-  const routes = []
+
+  const routes: Route[] = []
 
   const hooks: { [key in keyof RouterHooks]: RouterHooks[key][] } = {
     'navigate:before': [],
@@ -194,7 +194,7 @@ export default defineNuxtPlugin<{ route: Route, router: Router }>((nuxtApp) => {
         const route = router.resolve(props.to)
         return props.custom
           ? slots.default?.({ href: props.to, navigate, route })
-          : h('a', { href: props.to, onClick: (e) => { e.preventDefault(); return navigate() } }, slots)
+          : h('a', { href: props.to, onClick: (e: MouseEvent) => { e.preventDefault(); return navigate() } }, slots)
       }
     }
   })

packages/nuxt/src/auto-imports/module.ts

@@ -24,7 +24,7 @@ export default defineNuxtModule<Partial<AutoImportsOptions>>({
     // Allow modules extending sources
     await nuxt.callHook('autoImports:sources', options.presets as ImportPresetWithDeprecation[])
 
-    options.presets.forEach((i: ImportPresetWithDeprecation) => {
+    options.presets?.forEach((i: ImportPresetWithDeprecation | string) => {
       if (typeof i !== 'string' && i.names && !i.imports) {
         i.imports = i.names
         logger.warn('auto-imports: presets.names is deprecated, use presets.imports instead')
@@ -45,10 +45,13 @@ export default defineNuxtModule<Partial<AutoImportsOptions>>({
     })
 
     // composables/ dirs from all layers
-    let composablesDirs = []
+    let composablesDirs: string[] = []
     for (const layer of nuxt.options._layers) {
       composablesDirs.push(resolve(layer.config.srcDir, 'composables'))
       for (const dir of (layer.config.autoImports?.dirs ?? [])) {
+        if (!dir) {
+          continue
+        }
         composablesDirs.push(resolve(layer.config.srcDir, dir))
       }
     }
@@ -123,7 +126,7 @@ function addDeclarationTemplates (ctx: Unimport) {
   // Remove file extension for benefit of TypeScript
   const stripExtension = (path: string) => path.replace(/\.[a-z]+$/, '')
 
-  const resolved = {}
+  const resolved: Record<string, string> = {}
   const r = ({ from }: Import) => {
     if (resolved[from]) {
       return resolved[from]

packages/nuxt/src/core/app.ts

@@ -1,7 +1,7 @@
 import { promises as fsp } from 'node:fs'
 import { dirname, resolve } from 'pathe'
 import defu from 'defu'
-import type { Nuxt, NuxtApp, NuxtPlugin } from '@nuxt/schema'
+import type { Nuxt, NuxtApp, NuxtPlugin, NuxtTemplate } from '@nuxt/schema'
 import { findPath, resolveFiles, normalizePlugin, normalizeTemplate, compileTemplate, templateUtils, tryResolveModule, resolvePath, resolveAlias } from '@nuxt/kit'
 
 import * as defaultTemplates from './templates'
@@ -13,7 +13,7 @@ export function createApp (nuxt: Nuxt, options: Partial<NuxtApp> = {}): NuxtApp
     extensions: nuxt.options.extensions,
     plugins: [],
     templates: []
-  } as NuxtApp)
+  } as unknown as NuxtApp) as NuxtApp
 }
 
 export async function generateApp (nuxt: Nuxt, app: NuxtApp) {
@@ -21,7 +21,7 @@ export async function generateApp (nuxt: Nuxt, app: NuxtApp) {
   await resolveApp(nuxt, app)
 
   // User templates from options.build.templates
-  app.templates = Object.values(defaultTemplates).concat(nuxt.options.build.templates)
+  app.templates = Object.values(defaultTemplates).concat(nuxt.options.build.templates) as NuxtTemplate[]
 
   // Extend templates with hook
   await nuxt.callHook('app:templates', app)
@@ -34,10 +34,10 @@ export async function generateApp (nuxt: Nuxt, app: NuxtApp) {
   await Promise.all(app.templates.map(async (template) => {
     const contents = await compileTemplate(template, templateContext)
 
-    const fullPath = template.dst || resolve(nuxt.options.buildDir, template.filename)
+    const fullPath = template.dst || resolve(nuxt.options.buildDir, template.filename!)
     nuxt.vfs[fullPath] = contents
 
-    const aliasPath = '#build/' + template.filename.replace(/\.\w+$/, '')
+    const aliasPath = '#build/' + template.filename!.replace(/\.\w+$/, '')
     nuxt.vfs[aliasPath] = contents
 
     // In case a non-normalized absolute path is called for on Windows
@@ -102,10 +102,12 @@ export async function resolveApp (nuxt: Nuxt, app: NuxtApp) {
   for (const config of nuxt.options._layers.map(layer => layer.config)) {
     app.plugins.push(...[
       ...(config.plugins || []),
-      ...await resolveFiles(config.srcDir, [
+      ...config.srcDir
+        ? await resolveFiles(config.srcDir, [
           'plugins/*.{ts,js,mjs,cjs,mts,cts}',
           'plugins/*/index.*{ts,js,mjs,cjs,mts,cts}'
         ])
+        : []
     ].map(plugin => normalizePlugin(plugin as NuxtPlugin)))
   }
 

packages/nuxt/src/core/builder.ts

@@ -15,10 +15,10 @@ export async function build (nuxt: Nuxt) {
     nuxt.hook('builder:watch', async (event, path) => {
       if (event !== 'change' && /^(app\.|error\.|plugins\/|middleware\/|layouts\/)/i.test(path)) {
         if (path.startsWith('app')) {
-          app.mainComponent = null
+          app.mainComponent = undefined
         }
         if (path.startsWith('error')) {
-          app.errorComponent = null
+          app.errorComponent = undefined
         }
         await generateApp()
       }
@@ -38,7 +38,7 @@ export async function build (nuxt: Nuxt) {
 }
 
 function watch (nuxt: Nuxt) {
-  const watcher = chokidar.watch(nuxt.options._layers.map(i => i.config.srcDir), {
+  const watcher = chokidar.watch(nuxt.options._layers.map(i => i.config.srcDir as string).filter(Boolean), {
     ...nuxt.options.watchers.chokidar,
     cwd: nuxt.options.srcDir,
     ignoreInitial: true,
@@ -61,7 +61,7 @@ async function bundle (nuxt: Nuxt) {
       : nuxt.options.builder
 
     return bundle(nuxt)
-  } catch (error) {
+  } catch (error: any) {
     await nuxt.callHook('build:error', error)
 
     if (error.toString().includes('Cannot find module \'@nuxt/webpack-builder\'')) {

packages/nuxt/src/core/modules.ts

@@ -20,6 +20,7 @@ export const addModuleTranspiles = (opts: AddModuleTranspilesOptions = {}) => {
   // Try to sanitize modules to better match imports
   nuxt.options.build.transpile =
     nuxt.options.build.transpile.map(m => typeof m === 'string' ? m.split('node_modules/').pop() : m)
+      .filter(<T>(x: T | undefined): x is T => !!x)
 
   function isTranspilePresent (mod: string) {
     return nuxt.options.build.transpile.some(t => !(t instanceof Function) && (t instanceof RegExp ? t.test(mod) : new RegExp(t).test(mod)))

packages/nuxt/src/core/nitro.ts

@@ -22,7 +22,7 @@ export async function initNitro (nuxt: Nuxt) {
     dev: nuxt.options.dev,
     preset: nuxt.options.dev ? 'nitro-dev' : undefined,
     buildDir: nuxt.options.buildDir,
-    scanDirs: nuxt.options._layers.map(layer => join(layer.config.srcDir, 'server')),
+    scanDirs: nuxt.options._layers.map(layer => layer.config.srcDir).filter(Boolean).map(dir => join(dir!, 'server')),
     renderer: resolve(distDir, 'core/runtime/nitro/renderer'),
     errorHandler: resolve(distDir, 'core/runtime/nitro/error'),
     nodeModulesDirs: nuxt.options.modulesDir,
@@ -49,7 +49,7 @@ export async function initNitro (nuxt: Nuxt) {
     ],
     prerender: {
       crawlLinks: nuxt.options._generate ? nuxt.options.generate.crawler : false,
-      routes: []
+      routes: ([] as string[])
         .concat(nuxt.options._generate ? ['/', ...nuxt.options.generate.routes] : [])
         .concat(nuxt.options.ssr === false ? ['/', '/200.html', '/404.html'] : [])
     },
@@ -102,11 +102,11 @@ export async function initNitro (nuxt: Nuxt) {
 
   // Add fallback server for `ssr: false`
   if (!nuxt.options.ssr) {
-    nitroConfig.virtual['#build/dist/server/server.mjs'] = 'export default () => {}'
+    nitroConfig.virtual!['#build/dist/server/server.mjs'] = 'export default () => {}'
   }
 
   // Register nuxt protection patterns
-  nitroConfig.rollupConfig.plugins.push(ImportProtectionPlugin.rollup({
+  nitroConfig.rollupConfig!.plugins!.push(ImportProtectionPlugin.rollup({
     rootDir: nuxt.options.rootDir,
     patterns: [
       ...['#app', /^#build(\/|$)/]

packages/nuxt/src/core/nuxt.ts

@@ -81,7 +81,7 @@ async function initNuxt (nuxt: Nuxt) {
 
   // Transpile layers within node_modules
   nuxt.options.build.transpile.push(
-    ...nuxt.options._layers.filter(i => i.cwd && i.cwd.includes('node_modules')).map(i => i.cwd)
+    ...nuxt.options._layers.filter(i => i.cwd.includes('node_modules')).map(i => i.cwd as string)
   )
 
   // Init user modules
@@ -95,7 +95,7 @@ async function initNuxt (nuxt: Nuxt) {
   // Add <NuxtWelcome>
   addComponent({
     name: 'NuxtWelcome',
-    filePath: tryResolveModule('@nuxt/ui-templates/templates/welcome.vue')
+    filePath: tryResolveModule('@nuxt/ui-templates/templates/welcome.vue')!
   })
 
   addComponent({
@@ -165,7 +165,7 @@ export async function loadNuxt (opts: LoadNuxtOptions): Promise<Nuxt> {
     transform: {
       include: options._layers
         .filter(i => i.cwd && i.cwd.includes('node_modules'))
-        .map(i => new RegExp(`(^|\\/)${escapeRE(i.cwd.split('node_modules/').pop())}(\\/|$)(?!node_modules\\/)`))
+        .map(i => new RegExp(`(^|\\/)${escapeRE(i.cwd!.split('node_modules/').pop()!)}(\\/|$)(?!node_modules\\/)`))
     }
   }])
   options.modulesDir.push(resolve(pkgDir, 'node_modules'))

packages/nuxt/src/core/runtime/nitro/error.ts

@@ -1,16 +1,14 @@
 import { withQuery } from 'ufo'
 import type { NitroErrorHandler } from 'nitropack'
 import type { H3Error } from 'h3'
-// @ts-ignore TODO
 import { normalizeError, isJsonRequest } from '#internal/nitro/utils'
-import { NuxtApp } from '#app'
 
 export default <NitroErrorHandler> async function errorhandler (error: H3Error, event) {
   // Parse and normalize error
   const { stack, statusCode, statusMessage, message } = normalizeError(error)
 
   // Create an error object
-  const errorObject: Exclude<NuxtApp['payload']['error'], Error> = {
+  const errorObject = {
     url: event.req.url,
     statusCode,
     statusMessage,

packages/nuxt/src/core/runtime/nitro/renderer.ts

@@ -1,20 +1,15 @@
 import { createRenderer } from 'vue-bundle-renderer/runtime'
-import type { RenderHandler, RenderResponse } from 'nitropack'
+import type { RenderResponse } from 'nitropack'
 import type { Manifest } from 'vite'
-import { CompatibilityEvent, getQuery } from 'h3'
+import { getQuery } from 'h3'
 import devalue from '@nuxt/devalue'
 import { renderToString as _renderToString } from 'vue/server-renderer'
-import type { NuxtApp } from '#app'
+import type { NuxtApp, NuxtSSRContext } from '#app'
+import { useRuntimeConfig, useNitroApp, defineRenderHandler } from '#internal/nitro'
 
-// @ts-ignore
-import { useRuntimeConfig, useNitroApp, defineRenderHandler as _defineRenderHandler } from '#internal/nitro'
 // @ts-ignore
 import { buildAssetsURL } from '#paths'
 
-export type NuxtSSRContext = NuxtApp['ssrContext']
-
-const defineRenderHandler = _defineRenderHandler as (h: RenderHandler) => CompatibilityEvent
-
 export interface NuxtRenderHTMLContext {
   htmlAttrs: string[]
   head: string[]
@@ -31,10 +26,12 @@ export interface NuxtRenderResponse {
   headers: Record<string, string>
 }
 
+interface ClientManifest {}
+
 // @ts-ignore
 const getClientManifest: () => Promise<Manifest> = () => import('#build/dist/server/client.manifest.mjs')
   .then(r => r.default || r)
-  .then(r => typeof r === 'function' ? r() : r)
+  .then(r => typeof r === 'function' ? r() : r) as Promise<ClientManifest>
 
 // @ts-ignore
 const getServerEntry = () => import('#build/dist/server/server.mjs').then(r => r.default || r)
@@ -57,7 +54,8 @@ const getSSRRenderer = lazyCachedFunction(async () => {
   // Create renderer
   const renderer = createRenderer(createSSRApp, options)
 
-  async function renderToString (input, context) {
+  type RenderToStringParams = Parameters<typeof _renderToString>
+  async function renderToString (input: RenderToStringParams[0], context: RenderToStringParams[1]) {
     const html = await _renderToString(input, context)
     // In development with vite-node, the manifest is on-demand and will be available after rendering
     if (process.dev && process.env.NUXT_VITE_NODE_OPTIONS) {
@@ -84,14 +82,16 @@ const getSPARenderer = lazyCachedFunction(async () => {
 
   const renderToString = (ssrContext: NuxtSSRContext) => {
     const config = useRuntimeConfig()
-    ssrContext.payload = {
+    ssrContext!.payload = {
       serverRendered: false,
       config: {
         public: config.public,
         app: config.app
+      },
+      data: {},
+      state: {}
     }
-    }
+    ssrContext!.renderMeta = ssrContext!.renderMeta ?? (() => ({}))
-    ssrContext.renderMeta = ssrContext.renderMeta ?? (() => ({}))
     return Promise.resolve(result)
   }
 
@@ -109,23 +109,25 @@ export default defineRenderHandler(async (event) => {
     event,
     req: event.req,
     res: event.res,
-    runtimeConfig: useRuntimeConfig(),
+    runtimeConfig: useRuntimeConfig() as NuxtSSRContext['runtimeConfig'],
     noSSR: !!event.req.headers['x-nuxt-no-ssr'],
     error: !!ssrError,
-    nuxt: undefined, /* NuxtApp */
+    nuxt: undefined!, /* NuxtApp */
-    payload: ssrError ? { error: ssrError } : undefined
+    payload: ssrError ? { error: ssrError } as NuxtSSRContext['payload'] : undefined!
   }
 
   // Render app
   const renderer = (process.env.NUXT_NO_SSR || ssrContext.noSSR) ? await getSPARenderer() : await getSSRRenderer()
   const _rendered = await renderer.renderToString(ssrContext).catch((err) => {
-    if (!ssrError) { throw err }
+    if (!ssrError) {
+      throw err
+    }
   })
   await ssrContext.nuxt?.hooks.callHook('app:rendered', { ssrContext })
 
   // Handle errors
   if (!_rendered) {
-    return
+    return undefined!
   }
   if (ssrContext.payload?.error && !ssrError) {
     throw ssrContext.payload.error
@@ -143,7 +145,7 @@ export default defineRenderHandler(async (event) => {
       _rendered.renderStyles(),
       ssrContext.styles
     ]),
-    bodyAttrs: normalizeChunks([renderedMeta.bodyAttrs]),
+    bodyAttrs: normalizeChunks([renderedMeta.bodyAttrs!]),
     bodyPreprend: normalizeChunks([
       renderedMeta.bodyScriptsPrepend,
       ssrContext.teleports?.body
@@ -188,8 +190,8 @@ function lazyCachedFunction <T> (fn: () => Promise<T>): () => Promise<T> {
   }
 }
 
-function normalizeChunks (chunks: string[]) {
+function normalizeChunks (chunks: (string | undefined)[]) {
-  return chunks.filter(Boolean).map(i => i.trim())
+  return chunks.filter(Boolean).map(i => i!.trim())
 }
 
 function joinTags (tags: string[]) {

packages/nuxt/src/core/templates.ts

@@ -11,7 +11,7 @@ export interface TemplateContext {
   app: NuxtApp
 }
 
-export const vueShim = {
+export const vueShim: NuxtTemplate = {
   filename: 'types/vue-shim.d.ts',
   getContents: () =>
     [
@@ -24,29 +24,29 @@ export const vueShim = {
 }
 
 // TODO: Use an alias
-export const appComponentTemplate = {
+export const appComponentTemplate: NuxtTemplate<TemplateContext> = {
   filename: 'app-component.mjs',
-  getContents: (ctx: TemplateContext) => genExport(ctx.app.mainComponent, ['default'])
+  getContents: ctx => genExport(ctx.app.mainComponent!, ['default'])
 }
 // TODO: Use an alias
-export const rootComponentTemplate = {
+export const rootComponentTemplate: NuxtTemplate<TemplateContext> = {
   filename: 'root-component.mjs',
-  getContents: (ctx: TemplateContext) => genExport(ctx.app.rootComponent, ['default'])
+  getContents: ctx => genExport(ctx.app.rootComponent!, ['default'])
 }
 // TODO: Use an alias
-export const errorComponentTemplate = {
+export const errorComponentTemplate: NuxtTemplate<TemplateContext> = {
   filename: 'error-component.mjs',
-  getContents: (ctx: TemplateContext) => genExport(ctx.app.errorComponent, ['default'])
+  getContents: ctx => genExport(ctx.app.errorComponent!, ['default'])
 }
 
-export const cssTemplate = {
+export const cssTemplate: NuxtTemplate<TemplateContext> = {
   filename: 'css.mjs',
-  getContents: (ctx: TemplateContext) => ctx.nuxt.options.css.map(i => genImport(i)).join('\n')
+  getContents: ctx => ctx.nuxt.options.css.map(i => genImport(i)).join('\n')
 }
 
-export const clientPluginTemplate = {
+export const clientPluginTemplate: NuxtTemplate<TemplateContext> = {
   filename: 'plugins/client.mjs',
-  getContents (ctx: TemplateContext) {
+  getContents (ctx) {
     const clientPlugins = ctx.app.plugins.filter(p => !p.mode || p.mode !== 'server')
     const exports: string[] = []
     const imports: string[] = []
@@ -63,9 +63,9 @@ export const clientPluginTemplate = {
   }
 }
 
-export const serverPluginTemplate = {
+export const serverPluginTemplate: NuxtTemplate<TemplateContext> = {
   filename: 'plugins/server.mjs',
-  getContents (ctx: TemplateContext) {
+  getContents (ctx) {
     const serverPlugins = ctx.app.plugins.filter(p => !p.mode || p.mode !== 'client')
     const exports: string[] = ['preload']
     const imports: string[] = ["import preload from '#app/plugins/preload.server'"]
@@ -82,9 +82,9 @@ export const serverPluginTemplate = {
   }
 }
 
-export const pluginsDeclaration = {
+export const pluginsDeclaration: NuxtTemplate<TemplateContext> = {
   filename: 'types/plugins.d.ts',
-  getContents: (ctx: TemplateContext) => {
+  getContents: (ctx) => {
     const EXTENSION_RE = new RegExp(`(?<=\\w)(${ctx.nuxt.options.extensions.map(e => escapeRE(e)).join('|')})$`, 'g')
     const tsImports = ctx.app.plugins.map(p => (isAbsolute(p.src) ? relative(join(ctx.nuxt.options.buildDir, 'types'), p.src) : p.src).replace(EXTENSION_RE, ''))
 
@@ -111,9 +111,9 @@ export { }
 }
 
 const adHocModules = ['router', 'pages', 'auto-imports', 'meta', 'components']
-export const schemaTemplate = {
+export const schemaTemplate: NuxtTemplate<TemplateContext> = {
   filename: 'types/schema.d.ts',
-  getContents: ({ nuxt }: TemplateContext) => {
+  getContents: ({ nuxt }) => {
     const moduleInfo = nuxt.options._installedModules.map(m => ({
       ...m.meta || {},
       importName: m.entryPath || m.meta?.name
@@ -149,9 +149,9 @@ export const schemaTemplate = {
 }
 
 // Add layouts template
-export const layoutTemplate: NuxtTemplate = {
+export const layoutTemplate: NuxtTemplate<TemplateContext> = {
   filename: 'layouts.mjs',
-  getContents ({ app }: TemplateContext) {
+  getContents ({ app }) {
     const layoutsObject = genObjectFromRawEntries(Object.values(app.layouts).map(({ name, file }) => {
       return [name, `defineAsyncComponent(${genDynamicImport(file)})`]
     }))
@@ -163,9 +163,9 @@ export const layoutTemplate: NuxtTemplate = {
 }
 
 // Add middleware template
-export const middlewareTemplate: NuxtTemplate = {
+export const middlewareTemplate: NuxtTemplate<TemplateContext> = {
   filename: 'middleware.mjs',
-  getContents ({ app }: TemplateContext) {
+  getContents ({ app }) {
     const globalMiddleware = app.middleware.filter(mw => mw.global)
     const namedMiddleware = app.middleware.filter(mw => !mw.global)
     const namedMiddlewareObject = genObjectFromRawEntries(namedMiddleware.map(mw => [mw.name, genDynamicImport(mw.path)]))
@@ -184,7 +184,7 @@ export const useRuntimeConfig = () => window?.__NUXT__?.config || {}
 `
 }
 
-export const publicPathTemplate: NuxtTemplate = {
+export const publicPathTemplate: NuxtTemplate<TemplateContext> = {
   filename: 'paths.mjs',
   getContents ({ nuxt }) {
     return [

packages/nuxt/src/head/runtime/lib/vue-meta.plugin.ts

@@ -20,20 +20,20 @@ export default defineNuxtPlugin((nuxtApp) => {
   }
 
   if (process.server) {
-    nuxtApp.ssrContext.renderMeta = async () => {
+    nuxtApp.ssrContext!.renderMeta = async () => {
       // @ts-ignore
       const { renderMetaToString } = await import('vue-meta/ssr')
-      nuxtApp.ssrContext.teleports = nuxtApp.ssrContext.teleports || {}
+      nuxtApp.ssrContext!.teleports = nuxtApp.ssrContext!.teleports || {}
 
       await renderMetaToString(nuxtApp.app, nuxtApp.ssrContext)
 
       return {
-        htmlAttrs: nuxtApp.ssrContext.teleports.htmlAttrs || '',
+        htmlAttrs: nuxtApp.ssrContext!.teleports.htmlAttrs || '',
-        headAttrs: nuxtApp.ssrContext.teleports.headAttrs || '',
+        headAttrs: nuxtApp.ssrContext!.teleports.headAttrs || '',
-        bodyAttrs: nuxtApp.ssrContext.teleports.bodyAttrs || '',
+        bodyAttrs: nuxtApp.ssrContext!.teleports.bodyAttrs || '',
-        headTags: nuxtApp.ssrContext.teleports.head || '',
+        headTags: nuxtApp.ssrContext!.teleports.head || '',
-        bodyScriptsPrepend: nuxtApp.ssrContext.teleports['body-prepend'] || '',
+        bodyScriptsPrepend: nuxtApp.ssrContext!.teleports['body-prepend'] || '',
-        bodyScripts: nuxtApp.ssrContext.teleports.body || ''
+        bodyScripts: nuxtApp.ssrContext!.teleports.body || ''
       }
     }
   }

packages/nuxt/src/head/runtime/lib/vueuse-head.plugin.ts

@@ -45,7 +45,7 @@ export default defineNuxtPlugin((nuxtApp) => {
   }
 
   if (process.server) {
-    nuxtApp.ssrContext.renderMeta = () => {
+    nuxtApp.ssrContext!.renderMeta = () => {
       const meta = renderHeadToString(head)
       return {
         ...meta,

packages/nuxt/src/head/runtime/plugin.ts

@@ -34,6 +34,6 @@ export default defineNuxtPlugin((nuxtApp) => {
 
   for (const name in Components) {
     // eslint-disable-next-line import/namespace
-    nuxtApp.vueApp.component(name, Components[name])
+    nuxtApp.vueApp.component(name, (Components as any)[name])
   }
 })

packages/nuxt/src/pages/module.ts

@@ -47,7 +47,7 @@ export default defineNuxtModule({
 
     nuxt.hook('app:resolve', (app) => {
       // Add default layout for pages
-      if (app.mainComponent.includes('@nuxt/ui-templates')) {
+      if (app.mainComponent!.includes('@nuxt/ui-templates')) {
         app.mainComponent = resolve(runtimeDir, 'app.vue')
       }
     })

packages/nuxt/src/pages/runtime/page.ts

@@ -1,5 +1,5 @@
 import { computed, DefineComponent, defineComponent, h, inject, provide, reactive, Suspense, Transition } from 'vue'
-import { RouteLocationNormalized, RouteLocationNormalizedLoaded, RouterView } from 'vue-router'
+import { RouteLocation, RouteLocationNormalized, RouteLocationNormalizedLoaded, RouterView } from 'vue-router'
 
 import { generateRouteKey, RouterViewSlotProps, wrapInKeepAlive } from './utils'
 import { useNuxtApp } from '#app'
@@ -58,6 +58,7 @@ export default defineComponent({
 const defaultPageTransition = { name: 'page', mode: 'out-in' }
 
 const Component = defineComponent({
+  // TODO: Type props
   // eslint-disable-next-line vue/require-prop-types
   props: ['routeProps', 'pageKey'],
   setup (props) {
@@ -66,9 +67,9 @@ const Component = defineComponent({
     const previousRoute = props.routeProps.route
 
     // Provide a reactive route within the page
-    const route = {}
+    const route = {} as RouteLocation
     for (const key in props.routeProps.route) {
-      route[key] = computed(() => previousKey === props.pageKey ? props.routeProps.route[key] : previousRoute[key])
+      (route as any)[key] = computed(() => previousKey === props.pageKey ? props.routeProps.route[key] : previousRoute[key])
     }
 
     provide('_route', reactive(route))

packages/nuxt/src/pages/runtime/router.ts

@@ -59,7 +59,7 @@ export default defineNuxtPlugin(async (nuxtApp) => {
     ? createWebHistory(baseURL)
     : createMemoryHistory(baseURL)
 
-  const initialURL = process.server ? nuxtApp.ssrContext.url : createCurrentLocation(baseURL, window.location)
+  const initialURL = process.server ? nuxtApp.ssrContext!.url : createCurrentLocation(baseURL, window.location)
   const router = createRouter({
     ...routerOptions,
     history: routerHistory,
@@ -89,9 +89,9 @@ export default defineNuxtPlugin(async (nuxtApp) => {
   })
 
   // https://github.com/vuejs/router/blob/main/packages/router/src/router.ts#L1225-L1233
-  const route = {}
+  const route = {} as RouteLocation
   for (const key in _route.value) {
-    route[key] = computed(() => _route.value[key])
+    (route as any)[key] = computed(() => _route.value[key as keyof RouteLocation])
   }
 
   nuxtApp._route = reactive(route)
@@ -109,7 +109,7 @@ export default defineNuxtPlugin(async (nuxtApp) => {
     }
 
     await router.isReady()
-  } catch (error) {
+  } catch (error: any) {
     // We'll catch 404s here
     callWithNuxt(nuxtApp, showError, [error])
   }
@@ -133,7 +133,7 @@ export default defineNuxtPlugin(async (nuxtApp) => {
     }
 
     for (const entry of middlewareEntries) {
-      const middleware = typeof entry === 'string' ? nuxtApp._middleware.named[entry] || await namedMiddleware[entry]?.().then(r => r.default || r) : entry
+      const middleware = typeof entry === 'string' ? nuxtApp._middleware.named[entry] || await namedMiddleware[entry]?.().then((r: any) => r.default || r) : entry
 
       if (!middleware) {
         if (process.dev) {
@@ -169,7 +169,7 @@ export default defineNuxtPlugin(async (nuxtApp) => {
         statusMessage: `Page not found: ${to.fullPath}`
       })])
     } else if (process.server && to.matched[0].name === '404' && nuxtApp.ssrContext) {
-      nuxtApp.ssrContext.res.statusCode = 404
+      nuxtApp.ssrContext.event.res.statusCode = 404
     } else if (process.server) {
       const currentURL = to.fullPath || '/'
       if (!isEqual(currentURL, initialURL)) {
@@ -185,7 +185,7 @@ export default defineNuxtPlugin(async (nuxtApp) => {
         name: undefined, // #4920, #$4982
         force: true
       })
-    } catch (error) {
+    } catch (error: any) {
       // We'll catch middleware errors or deliberate exceptions here
       callWithNuxt(nuxtApp, showError, [error])
     }

packages/nuxt/src/pages/runtime/utils.ts

@@ -12,8 +12,8 @@ const interpolatePath = (route: RouteLocationNormalizedLoaded, match: RouteLocat
 }
 
 export const generateRouteKey = (override: string | ((route: RouteLocationNormalizedLoaded) => string), routeProps: RouterViewSlotProps) => {
-  const matchedRoute = routeProps.route.matched.find(m => m.components.default === routeProps.Component.type)
+  const matchedRoute = routeProps.route.matched.find(m => m.components?.default === routeProps.Component.type)
-  const source = override ?? matchedRoute?.meta.key ?? interpolatePath(routeProps.route, matchedRoute)
+  const source = override ?? matchedRoute?.meta.key ?? (matchedRoute && interpolatePath(routeProps.route, matchedRoute))
   return typeof source === 'function' ? source(routeProps.route) : source
 }
 

packages/nuxt/src/pages/utils.ts

@@ -76,7 +76,7 @@ export function generateRoutesFromFiles (files: string[], pagesDir: string): Nux
       // ex: parent.vue + parent/child.vue
       const child = parent.find(parentRoute => parentRoute.name === route.name && !parentRoute.path.endsWith('(.*)*'))
 
-      if (child) {
+      if (child && child.children) {
         parent = child.children
         route.path = ''
       } else if (segmentName === '404' && isSingleSegment) {
@@ -213,11 +213,11 @@ function prepareRoutes (routes: NuxtPage[], parent?: NuxtPage) {
       route.path = route.path.slice(1)
     }
 
-    if (route.children.length) {
+    if (route.children?.length) {
       route.children = prepareRoutes(route.children, route)
     }
 
-    if (route.children.find(childRoute => childRoute.path === '')) {
+    if (route.children?.find(childRoute => childRoute.path === '')) {
       delete route.name
     }
   }

packages/nuxt/test/nuxt-link.test.ts

@@ -8,7 +8,7 @@ vi.mock('vue', async () => {
   return {
     ...vue,
     resolveComponent: (name: string) => name,
-    h: (...args) => args
+    h: (...args: any[]) => args
   }
 })
 
@@ -17,7 +17,7 @@ vi.mock('#app', () => ({
   useRouter: () => ({ resolve: ({ to }: { to: string }) => ({ href: to }) })
 }))
 
-// Helpers for test lisibility
+// Helpers for test visibility
 const EXTERNAL = 'a'
 const INTERNAL = 'RouterLink'
 
@@ -44,7 +44,7 @@ describe('nuxt-link:to', () => {
   })
 
   it('renders link with `to` prop and warns about `href` prop conflict', () => {
-    const consoleWarnSpy = vi.spyOn(console, 'warn').mockImplementation(vi.fn())
+    const consoleWarnSpy = vi.spyOn(console, 'warn').mockImplementation(vi.fn() as any)
 
     expect(nuxtLink({ to: '/to', href: '/href' }).props.to).toBe('/to')
     // TODO: Uncomment when `dev` mode for tests is available
@@ -136,7 +136,7 @@ describe('nuxt-link:propsOrAttributes', () => {
       })
 
       it('honors `noRel` prop and warns about `rel` prop conflict', () => {
-        const consoleWarnSpy = vi.spyOn(console, 'warn').mockImplementation(vi.fn())
+        const consoleWarnSpy = vi.spyOn(console, 'warn').mockImplementation(vi.fn() as any)
 
         expect(nuxtLink({ to: 'https://nuxtjs.org', noRel: true, rel: 'foo' }).props.rel).toBe(null)
         // TODO: Uncomment when `dev` mode for tests is available

packages/nuxt/tsconfig.json

@@ -0,0 +1,11 @@
+{
+  "extends": "../../tsconfig.json",
+  "compilerOptions": {
+    "strict": true,
+    "noImplicitAny": true
+  },
+  "include": [
+    "./src/**/*.ts",
+    "./test/**/*.ts"
+  ]
+}

packages/schema/src/types/config.ts

@@ -1,5 +1,4 @@
 import { ConfigSchema } from '../../schema/config'
-import type { ResolvedConfig } from 'c12'
 import type { UserConfig as ViteUserConfig } from 'vite'
 import type { Options as VuePluginOptions } from '@vitejs/plugin-vue'
 
@@ -12,9 +11,20 @@ export interface NuxtConfig extends DeepPartial<Omit<ConfigSchema, 'vite'>> {
   [key: string]: any
 }
 
+// TODO: Expose ConfigLayer<T> from c12
+interface ConfigLayer<T> {
+  config: T;
+  cwd: string;
+  configFile: string
+}
+export type NuxtConfigLayer = ConfigLayer<NuxtConfig & {
+  srcDir: ConfigSchema['srcDir'],
+  rootDir: ConfigSchema['rootDir']
+}>
+
 /** Normalized Nuxt options available as `nuxt.options.*` */
 export interface NuxtOptions extends ConfigSchema {
-  _layers: ResolvedConfig<NuxtConfig>[]
+  _layers: NuxtConfigLayer[]
 }
 
 type RuntimeConfigNamespace = Record<string, any>

packages/schema/src/types/nuxt.ts

@@ -24,7 +24,7 @@ export interface Nuxt {
   vfs: Record<string, string>
 }
 
-export interface NuxtTemplate {
+export interface NuxtTemplate<Options = Record<string, any>> {
   /** @deprecated filename */
   fileName?: string
   /** @deprecated whether template is custom or a nuxt core template */
@@ -51,9 +51,9 @@ export interface NuxtPlugin {
 }
 
 export interface NuxtApp {
-  mainComponent?: string
+  mainComponent?: string | null
-  rootComponent?: string
+  rootComponent?: string | null
-  errorComponent?: string
+  errorComponent?: string | null
   dir: string
   extensions: string[]
   plugins: NuxtPlugin[]

test/fixtures/basic/types.ts

@@ -4,8 +4,8 @@ import type { Ref } from 'vue'
 
 import { NavigationFailure, RouteLocationNormalizedLoaded, RouteLocationRaw, useRouter as vueUseRouter } from 'vue-router'
 import { defineNuxtConfig } from '~~/../../../packages/nuxt/src'
-import { useRouter } from '#imports'
 import { isVue3 } from '#app'
+import { useRouter } from '#imports'
 
 interface TestResponse { message: string }
 

tsconfig.json

@@ -8,6 +8,7 @@
     "moduleResolution": "Node",
     "strict": false,
     "allowJs": true,
+    "noEmit": true,
     "noUnusedLocals": true,
     "resolveJsonModule": true,
     "types": [
@@ -23,6 +24,12 @@
       "#head": [
         "./packages/nuxt/src/head/runtime/index"
       ],
+      "#internal/nitro": [
+        "./node_modules/nitropack/dist/runtime"
+      ],
+      "#internal/nitro/utils": [
+        "./node_modules/nitropack/dist/runtime/utils"
+      ]
     }
   },
   "exclude": [