diff --git a/packages/nuxt/src/app/components/client-fallback.server.ts b/packages/nuxt/src/app/components/client-fallback.server.ts
index c1bc3c3e02..dd4e0cdb28 100644
--- a/packages/nuxt/src/app/components/client-fallback.server.ts
+++ b/packages/nuxt/src/app/components/client-fallback.server.ts
@@ -54,8 +54,10 @@ const NuxtClientFallbackServer = defineComponent({
       const defaultSlot = ctx.slots.default?.()
       const ssrVNodes = createBuffer()
 
-      for (let i = 0; i < (defaultSlot?.length || 0); i++) {
-        ssrRenderVNode(ssrVNodes.push, defaultSlot![i], vm!)
+      if (defaultSlot) {
+        for (let i = 0; i < defaultSlot.length; i++) {
+          ssrRenderVNode(ssrVNodes.push, defaultSlot[i]!, vm!)
+        }
       }
 
       const buffer = ssrVNodes.getBuffer()
diff --git a/packages/nuxt/src/app/components/nuxt-island.ts b/packages/nuxt/src/app/components/nuxt-island.ts
index 937f9d3136..c6bb6d8657 100644
--- a/packages/nuxt/src/app/components/nuxt-island.ts
+++ b/packages/nuxt/src/app/components/nuxt-island.ts
@@ -29,17 +29,20 @@ const getId = import.meta.client ? () => (id++).toString() : randomUUID
 const components = import.meta.client ? new Map<string, Component>() : undefined
 
 async function loadComponents (source = appBaseURL, paths: NuxtIslandResponse['components']) {
+  if (!paths) { return }
+
   const promises: Array<Promise<void>> = []
 
-  for (const component in paths) {
+  for (const [component, item] of Object.entries(paths)) {
     if (!(components!.has(component))) {
       promises.push((async () => {
-        const chunkSource = join(source, paths[component].chunk)
+        const chunkSource = join(source, item.chunk)
         const c = await import(/* @vite-ignore */ chunkSource).then(m => m.default || m)
         components!.set(component, c)
       })())
     }
   }
+
   await Promise.all(promises)
 }
 
@@ -276,7 +279,7 @@ export default defineComponent({
                 teleports.push(createVNode(Teleport,
                   // use different selectors for even and odd teleportKey to force trigger the teleport
                   { to: import.meta.client ? `${isKeyOdd ? 'div' : ''}[data-island-uid="${uid.value}"][data-island-slot="${slot}"]` : `uid=${uid.value};slot=${slot}` },
-                  { default: () => (payloads.slots?.[slot].props?.length ? payloads.slots[slot].props : [{}]).map((data: any) => slots[slot]?.(data)) }),
+                  { default: () => (payloads.slots?.[slot]?.props?.length ? payloads.slots[slot].props : [{}]).map((data: any) => slots[slot]?.(data)) }),
                 )
               }
             }
diff --git a/packages/nuxt/src/app/components/nuxt-teleport-island-component.ts b/packages/nuxt/src/app/components/nuxt-teleport-island-component.ts
index 875204ccf4..b8ef06f9c4 100644
--- a/packages/nuxt/src/app/components/nuxt-teleport-island-component.ts
+++ b/packages/nuxt/src/app/components/nuxt-teleport-island-component.ts
@@ -39,7 +39,7 @@ export default defineComponent({
     const islandContext = nuxtApp.ssrContext!.islandContext!
 
     return () => {
-      const slot = slots.default!()[0]
+      const slot = slots.default!()[0]!
       const slotType = slot.type as ExtendedComponent
       const name = (slotType.__name || slotType.name) as string
 
diff --git a/packages/nuxt/src/app/components/utils.ts b/packages/nuxt/src/app/components/utils.ts
index bb16708588..0bde127ec5 100644
--- a/packages/nuxt/src/app/components/utils.ts
+++ b/packages/nuxt/src/app/components/utils.ts
@@ -100,7 +100,7 @@ export function vforToArray (source: any): any[] {
       const keys = Object.keys(source)
       const array = new Array(keys.length)
       for (let i = 0, l = keys.length; i < l; i++) {
-        const key = keys[i]
+        const key = keys[i]!
         array[i] = source[key]
       }
       return array
diff --git a/packages/nuxt/src/app/composables/payload.ts b/packages/nuxt/src/app/composables/payload.ts
index 1708bbad99..e24d34feab 100644
--- a/packages/nuxt/src/app/composables/payload.ts
+++ b/packages/nuxt/src/app/composables/payload.ts
@@ -23,7 +23,7 @@ export async function loadPayload (url: string, opts: LoadPayloadOptions = {}):
   const nuxtApp = useNuxtApp()
   const cache = nuxtApp._payloadCache = nuxtApp._payloadCache || {}
   if (payloadURL in cache) {
-    return cache[payloadURL]
+    return cache[payloadURL] || null
   }
   cache[payloadURL] = isPrerendered(url).then((prerendered) => {
     if (!prerendered) {
diff --git a/packages/nuxt/src/app/composables/preload.ts b/packages/nuxt/src/app/composables/preload.ts
index 1358273b8a..cac6f5c85a 100644
--- a/packages/nuxt/src/app/composables/preload.ts
+++ b/packages/nuxt/src/app/composables/preload.ts
@@ -14,7 +14,12 @@ export const preloadComponents = async (components: string | string[]) => {
   const nuxtApp = useNuxtApp()
 
   components = toArray(components)
-  await Promise.all(components.map(name => _loadAsyncComponent(nuxtApp.vueApp._context.components[name])))
+  await Promise.all(components.map((name) => {
+    const component = nuxtApp.vueApp._context.components[name]
+    if (component) {
+      return _loadAsyncComponent(component)
+    }
+  }))
 }
 
 /**
diff --git a/packages/nuxt/src/app/plugins/revive-payload.client.ts b/packages/nuxt/src/app/plugins/revive-payload.client.ts
index 3ab2f211df..2d2c2e8bbd 100644
--- a/packages/nuxt/src/app/plugins/revive-payload.client.ts
+++ b/packages/nuxt/src/app/plugins/revive-payload.client.ts
@@ -7,18 +7,18 @@ import { defineNuxtPlugin, useNuxtApp } from '../nuxt'
 // @ts-expect-error Virtual file.
 import { componentIslands } from '#build/nuxt.config.mjs'
 
-const revivers: Record<string, (data: any) => any> = {
-  NuxtError: data => createError(data),
-  EmptyShallowRef: data => shallowRef(data === '_' ? undefined : data === '0n' ? BigInt(0) : destr(data)),
-  EmptyRef: data => ref(data === '_' ? undefined : data === '0n' ? BigInt(0) : destr(data)),
-  ShallowRef: data => shallowRef(data),
-  ShallowReactive: data => shallowReactive(data),
-  Ref: data => ref(data),
-  Reactive: data => reactive(data),
-}
+const revivers: [string, (data: any) => any][] = [
+  ['NuxtError', data => createError(data)],
+  ['EmptyShallowRef', data => shallowRef(data === '_' ? undefined : data === '0n' ? BigInt(0) : destr(data))],
+  ['EmptyRef', data => ref(data === '_' ? undefined : data === '0n' ? BigInt(0) : destr(data))],
+  ['ShallowRef', data => shallowRef(data)],
+  ['ShallowReactive', data => shallowReactive(data)],
+  ['Ref', data => ref(data)],
+  ['Reactive', data => reactive(data)],
+]
 
 if (componentIslands) {
-  revivers.Island = ({ key, params, result }: any) => {
+  revivers.push(['Island', ({ key, params, result }: any) => {
     const nuxtApp = useNuxtApp()
     if (!nuxtApp.isHydrating) {
       nuxtApp.payload.data[key] = nuxtApp.payload.data[key] || $fetch(`/__nuxt_island/${key}.json`, {
@@ -33,15 +33,15 @@ if (componentIslands) {
       html: '',
       ...result,
     }
-  }
+  }])
 }
 
 export default defineNuxtPlugin({
   name: 'nuxt:revive-payload:client',
   order: -30,
   async setup (nuxtApp) {
-    for (const reviver in revivers) {
-      definePayloadReviver(reviver, revivers[reviver as keyof typeof revivers])
+    for (const [reviver, fn] of revivers) {
+      definePayloadReviver(reviver, fn)
     }
     Object.assign(nuxtApp.payload, await nuxtApp.runWithContext(getNuxtClientPayload))
     delete window.__NUXT__
diff --git a/packages/nuxt/src/components/islandsTransform.ts b/packages/nuxt/src/components/islandsTransform.ts
index d583e3425d..e01b2ea3cc 100644
--- a/packages/nuxt/src/components/islandsTransform.ts
+++ b/packages/nuxt/src/components/islandsTransform.ts
@@ -78,7 +78,7 @@ export const islandsTransform = createUnplugin((options: ServerOnlyComponentTran
 
             if (attributes.name) { delete attributes.name }
             if (attributes['v-bind']) {
-              attributes._bind = extractAttributes(attributes, ['v-bind'])['v-bind']
+              attributes._bind = extractAttributes(attributes, ['v-bind'])['v-bind']!
             }
             const teleportAttributes = extractAttributes(attributes, ['v-if', 'v-else-if', 'v-else'])
             const bindings = getPropsToString(attributes)
@@ -137,7 +137,7 @@ function extractAttributes (attributes: Record<string, string>, names: string[])
   const extracted: Record<string, string> = {}
   for (const name of names) {
     if (name in attributes) {
-      extracted[name] = attributes[name]
+      extracted[name] = attributes[name]!
       delete attributes[name]
     }
   }
diff --git a/packages/nuxt/src/components/module.ts b/packages/nuxt/src/components/module.ts
index 34da7e1c71..dbfd5b9653 100644
--- a/packages/nuxt/src/components/module.ts
+++ b/packages/nuxt/src/components/module.ts
@@ -140,10 +140,10 @@ export default defineNuxtModule<ComponentsOptions>({
     nuxt.hook('build:manifest', (manifest) => {
       const sourceFiles = getComponents().filter(c => c.global).map(c => relative(nuxt.options.srcDir, c.filePath))
 
-      for (const key in manifest) {
-        if (manifest[key].isEntry) {
-          manifest[key].dynamicImports =
-            manifest[key].dynamicImports?.filter(i => !sourceFiles.includes(i))
+      for (const chunk of Object.values(manifest)) {
+        if (chunk.isEntry) {
+          chunk.dynamicImports =
+            chunk.dynamicImports?.filter(i => !sourceFiles.includes(i))
         }
       }
     })
diff --git a/packages/nuxt/src/components/tree-shake.ts b/packages/nuxt/src/components/tree-shake.ts
index 56ea65cd3b..8108a9434d 100644
--- a/packages/nuxt/src/components/tree-shake.ts
+++ b/packages/nuxt/src/components/tree-shake.ts
@@ -56,6 +56,8 @@ export const TreeShakeTemplatePlugin = createUnplugin((options: TreeShakeTemplat
           const node = _node as AcornNode<Node>
           if (isSsrRender(node)) {
             const [componentCall, _, children] = node.arguments
+            if (!componentCall) { return }
+
             if (componentCall.type === 'Identifier' || componentCall.type === 'MemberExpression' || componentCall.type === 'CallExpression') {
               const componentName = getComponentName(node)
               const isClientComponent = COMPONENTS_IDENTIFIERS_RE.test(componentName)
@@ -137,8 +139,10 @@ function removeFromSetupReturn (codeAst: Program, name: string, magicString: Mag
           const variableList = node.value.body.body.filter((statement): statement is VariableDeclaration => statement.type === 'VariableDeclaration')
           const returnedVariableDeclaration = variableList.find(declaration => declaration.declarations[0]?.id.type === 'Identifier' && declaration.declarations[0]?.id.name === '__returned__' && declaration.declarations[0]?.init?.type === 'ObjectExpression')
           if (returnedVariableDeclaration) {
-            const init = returnedVariableDeclaration.declarations[0].init as ObjectExpression
-            removePropertyFromObject(init, name, magicString)
+            const init = returnedVariableDeclaration.declarations[0]?.init as ObjectExpression | undefined
+            if (init) {
+              removePropertyFromObject(init, name, magicString)
+            }
           }
         }
       }
diff --git a/packages/nuxt/src/core/app.ts b/packages/nuxt/src/core/app.ts
index 494b30b798..50ac4118e5 100644
--- a/packages/nuxt/src/core/app.ts
+++ b/packages/nuxt/src/core/app.ts
@@ -254,7 +254,7 @@ export async function annotatePlugins (nuxt: Nuxt, plugins: NuxtPlugin[]) {
   const _plugins: Array<NuxtPlugin & Omit<PluginMeta, 'enforce'>> = []
   for (const plugin of plugins) {
     try {
-      const code = plugin.src in nuxt.vfs ? nuxt.vfs[plugin.src] : await fsp.readFile(plugin.src!, 'utf-8')
+      const code = plugin.src in nuxt.vfs ? nuxt.vfs[plugin.src]! : await fsp.readFile(plugin.src!, 'utf-8')
       _plugins.push({
         ...await extractMetadata(code, IS_TSX.test(plugin.src) ? 'tsx' : 'ts'),
         ...plugin,
diff --git a/packages/nuxt/src/core/builder.ts b/packages/nuxt/src/core/builder.ts
index b414cbf081..1e8d7eb0e1 100644
--- a/packages/nuxt/src/core/builder.ts
+++ b/packages/nuxt/src/core/builder.ts
@@ -138,9 +138,9 @@ function createGranularWatcher () {
         delete watchers[path]
       }
       if (event === 'addDir' && path !== dir && !ignoredDirs.has(path) && !pathsToWatch.includes(path) && !(path in watchers) && !isIgnored(path)) {
-        watchers[path] = chokidarWatch(path, { ...nuxt.options.watchers.chokidar, ignored: [isIgnored] })
-        watchers[path].on('all', (event, p) => nuxt.callHook('builder:watch', event, normalize(p)))
-        nuxt.hook('close', () => watchers[path]?.close())
+        const pathWatcher = watchers[path] = chokidarWatch(path, { ...nuxt.options.watchers.chokidar, ignored: [isIgnored] })
+        pathWatcher.on('all', (event, p) => nuxt.callHook('builder:watch', event, normalize(p)))
+        nuxt.hook('close', () => pathWatcher?.close())
       }
     })
     watcher.on('ready', () => {
diff --git a/packages/nuxt/src/core/nitro.ts b/packages/nuxt/src/core/nitro.ts
index 33efcf3331..f2016c2175 100644
--- a/packages/nuxt/src/core/nitro.ts
+++ b/packages/nuxt/src/core/nitro.ts
@@ -102,7 +102,7 @@ export async function initNitro (nuxt: Nuxt & { _nitro?: Nitro }) {
     baseURL: nuxt.options.app.baseURL,
     virtual: {
       '#internal/nuxt.config.mjs': () => nuxt.vfs['#build/nuxt.config'],
-      '#internal/nuxt/app-config': () => nuxt.vfs['#build/app.config'].replace(/\/\*\* client \*\*\/[\s\S]*\/\*\* client-end \*\*\//, ''),
+      '#internal/nuxt/app-config': () => nuxt.vfs['#build/app.config']?.replace(/\/\*\* client \*\*\/[\s\S]*\/\*\* client-end \*\*\//, ''),
       '#spa-template': async () => `export const template = ${JSON.stringify(await spaLoadingTemplate(nuxt))}`,
     },
     routeRules: {
diff --git a/packages/nuxt/src/core/nuxt.ts b/packages/nuxt/src/core/nuxt.ts
index 3549e0858f..a2b9c894da 100644
--- a/packages/nuxt/src/core/nuxt.ts
+++ b/packages/nuxt/src/core/nuxt.ts
@@ -345,10 +345,10 @@ async function initNuxt (nuxt: Nuxt) {
   // TODO: [Experimental] Avoid emitting assets when flag is enabled
   if (nuxt.options.features.noScripts && !nuxt.options.dev) {
     nuxt.hook('build:manifest', async (manifest) => {
-      for (const file in manifest) {
-        if (manifest[file].resourceType === 'script') {
-          await rm(resolve(nuxt.options.buildDir, 'dist/client', withoutLeadingSlash(nuxt.options.app.buildAssetsDir), manifest[file].file), { force: true })
-          manifest[file].file = ''
+      for (const chunk of Object.values(manifest)) {
+        if (chunk.resourceType === 'script') {
+          await rm(resolve(nuxt.options.buildDir, 'dist/client', withoutLeadingSlash(nuxt.options.app.buildAssetsDir), chunk.file), { force: true })
+          chunk.file = ''
         }
       }
     })
diff --git a/packages/nuxt/src/core/plugins/layer-aliasing.ts b/packages/nuxt/src/core/plugins/layer-aliasing.ts
index 852cb0f281..dd5de8b88b 100644
--- a/packages/nuxt/src/core/plugins/layer-aliasing.ts
+++ b/packages/nuxt/src/core/plugins/layer-aliasing.ts
@@ -64,7 +64,7 @@ export const LayerAliasingPlugin = createUnplugin((options: LayerAliasingOptions
       if (!layer || !ALIAS_RE_SINGLE.test(code)) { return }
 
       const s = new MagicString(code)
-      s.replace(ALIAS_RE, r => aliases[layer][r as '~'] || r)
+      s.replace(ALIAS_RE, r => aliases[layer]?.[r as '~'] || r)
 
       if (s.hasChanged()) {
         return {
diff --git a/packages/nuxt/src/core/plugins/plugin-metadata.ts b/packages/nuxt/src/core/plugins/plugin-metadata.ts
index b59e2fa36d..6d94a770be 100644
--- a/packages/nuxt/src/core/plugins/plugin-metadata.ts
+++ b/packages/nuxt/src/core/plugins/plugin-metadata.ts
@@ -70,7 +70,7 @@ export async function extractMetadata (code: string, loader = 'ts' as 'ts' | 'ts
       }
 
       const plugin = node.arguments[0]
-      if (plugin.type === 'ObjectExpression') {
+      if (plugin?.type === 'ObjectExpression') {
         meta = defu(extractMetaFromObject(plugin.properties), meta)
       }
 
@@ -122,7 +122,7 @@ export const RemovePluginMetadataPlugin = (nuxt: Nuxt) => createUnplugin(() => {
     name: 'nuxt:remove-plugin-metadata',
     transform (code, id) {
       id = normalize(id)
-      const plugin = nuxt.apps.default.plugins.find(p => p.src === id)
+      const plugin = nuxt.apps.default?.plugins.find(p => p.src === id)
       if (!plugin) { return }
 
       const s = new MagicString(code)
diff --git a/packages/nuxt/src/core/plugins/prehydrate.ts b/packages/nuxt/src/core/plugins/prehydrate.ts
index e47fa3883e..c91e3cb5f7 100644
--- a/packages/nuxt/src/core/plugins/prehydrate.ts
+++ b/packages/nuxt/src/core/plugins/prehydrate.ts
@@ -32,6 +32,7 @@ export function prehydrateTransformPlugin (nuxt: Nuxt) {
           const node = _node as SimpleCallExpression & { start: number, end: number }
           const name = 'name' in node.callee && node.callee.name
           if (name === 'onPrehydrate') {
+            if (!node.arguments[0]) { return }
             if (node.arguments[0].type !== 'ArrowFunctionExpression' && node.arguments[0].type !== 'FunctionExpression') { return }
 
             const needsAttr = node.arguments[0].params.length > 0
diff --git a/packages/nuxt/src/core/runtime/nitro/renderer.ts b/packages/nuxt/src/core/runtime/nitro/renderer.ts
index 000e2facc4..e973d53f8e 100644
--- a/packages/nuxt/src/core/runtime/nitro/renderer.ts
+++ b/packages/nuxt/src/core/runtime/nitro/renderer.ts
@@ -325,7 +325,9 @@ export default defineRenderHandler(async (event): Promise<Partial<RenderResponse
   // Render 103 Early Hints
   if (process.env.NUXT_EARLY_HINTS && !isRenderingPayload && !import.meta.prerender) {
     const { link } = renderResourceHeaders({}, renderer.rendererContext)
-    writeEarlyHints(event, link)
+    if (link) {
+      writeEarlyHints(event, link)
+    }
   }
 
   if (process.env.NUXT_INLINE_STYLES && !isRenderingIsland) {
@@ -394,8 +396,7 @@ export default defineRenderHandler(async (event): Promise<Partial<RenderResponse
   }
   if (!isRenderingIsland || import.meta.dev) {
     const link: Link[] = []
-    for (const style in styles) {
-      const resource = styles[style]
+    for (const resource of Object.values(styles)) {
       // Do not add links to resources that are inlined (vite v5+)
       if (import.meta.dev && 'inline' in getURLQuery(resource.file)) {
         continue
@@ -566,7 +567,7 @@ async function renderInlineStyles (usedModules: Set<string> | string[]): Promise
   const styleMap = await getSSRStyles()
   const inlinedStyles = new Set<string>()
   for (const mod of usedModules) {
-    if (mod in styleMap) {
+    if (mod in styleMap && styleMap[mod]) {
       for (const style of await styleMap[mod]()) {
         inlinedStyles.add(style)
       }
@@ -650,7 +651,7 @@ function splitPayload (ssrContext: NuxtSSRContext) {
  */
 function getServerComponentHTML (body: string): string {
   const match = body.match(ROOT_NODE_REGEX)
-  return match ? match[1] : body[0]
+  return match?.[1] || body
 }
 
 const SSR_SLOT_TELEPORT_MARKER = /^uid=([^;]*);slot=(.*)$/
@@ -660,10 +661,10 @@ const SSR_CLIENT_SLOT_MARKER = /^island-slot=[^;]*;(.*)$/
 function getSlotIslandResponse (ssrContext: NuxtSSRContext): NuxtIslandResponse['slots'] {
   if (!ssrContext.islandContext || !Object.keys(ssrContext.islandContext.slots).length) { return undefined }
   const response: NuxtIslandResponse['slots'] = {}
-  for (const slot in ssrContext.islandContext.slots) {
-    response[slot] = {
-      ...ssrContext.islandContext.slots[slot],
-      fallback: ssrContext.teleports?.[`island-fallback=${slot}`],
+  for (const [name, slot] of Object.entries(ssrContext.islandContext.slots)) {
+    response[name] = {
+      ...slot,
+      fallback: ssrContext.teleports?.[`island-fallback=${name}`],
     }
   }
   return response
@@ -673,11 +674,11 @@ function getClientIslandResponse (ssrContext: NuxtSSRContext): NuxtIslandRespons
   if (!ssrContext.islandContext || !Object.keys(ssrContext.islandContext.components).length) { return undefined }
   const response: NuxtIslandResponse['components'] = {}
 
-  for (const clientUid in ssrContext.islandContext.components) {
+  for (const [clientUid, component] of Object.entries(ssrContext.islandContext.components)) {
     // remove teleport anchor to avoid hydration issues
-    const html = ssrContext.teleports?.[clientUid].replaceAll('<!--teleport start anchor-->', '') || ''
+    const html = ssrContext.teleports?.[clientUid]?.replaceAll('<!--teleport start anchor-->', '') || ''
     response[clientUid] = {
-      ...ssrContext.islandContext.components[clientUid],
+      ...component,
       html,
       slots: getComponentSlotTeleport(ssrContext.teleports ?? {}),
     }
diff --git a/packages/nuxt/src/core/utils/names.ts b/packages/nuxt/src/core/utils/names.ts
index 3397cc99e7..df6732c96f 100644
--- a/packages/nuxt/src/core/utils/names.ts
+++ b/packages/nuxt/src/core/utils/names.ts
@@ -28,11 +28,12 @@ export function resolveComponentNameSegments (fileName: string, prefixParts: str
   let index = prefixParts.length - 1
   const matchedSuffix: string[] = []
   while (index >= 0) {
-    matchedSuffix.unshift(...splitByCase(prefixParts[index]).map(p => p.toLowerCase()))
+    const prefixPart = prefixParts[index]!
+    matchedSuffix.unshift(...splitByCase(prefixPart).map(p => p.toLowerCase()))
     const matchedSuffixContent = matchedSuffix.join('/')
     if ((fileNamePartsContent === matchedSuffixContent || fileNamePartsContent.startsWith(matchedSuffixContent + '/')) ||
       // e.g Item/Item/Item.vue -> Item
-      (prefixParts[index].toLowerCase() === fileNamePartsContent &&
+      (prefixPart.toLowerCase() === fileNamePartsContent &&
         prefixParts[index + 1] &&
         prefixParts[index] === prefixParts[index + 1])) {
       componentNameParts.length = index
diff --git a/packages/nuxt/src/head/runtime/components.ts b/packages/nuxt/src/head/runtime/components.ts
index 7c3f4b8140..5913471dde 100644
--- a/packages/nuxt/src/head/runtime/components.ts
+++ b/packages/nuxt/src/head/runtime/components.ts
@@ -160,7 +160,7 @@ export const Title = defineComponent({
     if (import.meta.dev) {
       const defaultSlot = slots.default?.()
 
-      if (defaultSlot && (defaultSlot.length > 1 || typeof defaultSlot[0].children !== 'string')) {
+      if (defaultSlot && (defaultSlot.length > 1 || (defaultSlot[0] && typeof defaultSlot[0].children !== 'string'))) {
         console.error('<Title> can take only one string in its default slot.')
       }
 
diff --git a/packages/nuxt/src/pages/module.ts b/packages/nuxt/src/pages/module.ts
index 5e79e31746..ee7c937182 100644
--- a/packages/nuxt/src/pages/module.ts
+++ b/packages/nuxt/src/pages/module.ts
@@ -247,7 +247,7 @@ export default defineNuxtModule({
       ]
     })
 
-    function isPage (file: string, pages = nuxt.apps.default.pages): boolean {
+    function isPage (file: string, pages = nuxt.apps.default?.pages): boolean {
       if (!pages) { return false }
       return pages.some(page => page.file === file) || pages.some(page => page.children && isPage(file, page.children))
     }
@@ -359,7 +359,7 @@ export default defineNuxtModule({
 
       const updatePage = async function updatePage (path: string) {
         const glob = pageToGlobMap[path]
-        const code = path in nuxt.vfs ? nuxt.vfs[path] : await readFile(path!, 'utf-8')
+        const code = path in nuxt.vfs ? nuxt.vfs[path]! : await readFile(path!, 'utf-8')
         try {
           const extractedRule = await extractRouteRules(code)
           if (extractedRule) {
@@ -408,8 +408,7 @@ export default defineNuxtModule({
       nuxt.hook('pages:extend', (routes) => {
         const nitro = useNitro()
         let resolvedRoutes: string[]
-        for (const path in nitro.options.routeRules) {
-          const rule = nitro.options.routeRules[path]
+        for (const [path, rule] of Object.entries(nitro.options.routeRules)) {
           if (!rule.redirect) { continue }
           resolvedRoutes ||= routes.flatMap(route => resolveRoutePaths(route))
           // skip if there's already a route matching this path
@@ -455,14 +454,14 @@ export default defineNuxtModule({
       if (nuxt.options.dev) { return }
       const sourceFiles = nuxt.apps.default?.pages?.length ? getSources(nuxt.apps.default.pages) : []
 
-      for (const key in manifest) {
-        if (manifest[key].src && Object.values(nuxt.apps).some(app => app.pages?.some(page => page.mode === 'server' && page.file === join(nuxt.options.srcDir, manifest[key].src!)))) {
+      for (const [key, chunk] of Object.entries(manifest)) {
+        if (chunk.src && Object.values(nuxt.apps).some(app => app.pages?.some(page => page.mode === 'server' && page.file === join(nuxt.options.srcDir, chunk.src!)))) {
           delete manifest[key]
           continue
         }
-        if (manifest[key].isEntry) {
-          manifest[key].dynamicImports =
-            manifest[key].dynamicImports?.filter(i => !sourceFiles.includes(i))
+        if (chunk.isEntry) {
+          chunk.dynamicImports =
+            chunk.dynamicImports?.filter(i => !sourceFiles.includes(i))
         }
       }
     })
diff --git a/packages/nuxt/src/pages/route-rules.ts b/packages/nuxt/src/pages/route-rules.ts
index 6f025f678e..1b76a75b52 100644
--- a/packages/nuxt/src/pages/route-rules.ts
+++ b/packages/nuxt/src/pages/route-rules.ts
@@ -14,7 +14,7 @@ const ruleCache: Record<string, NitroRouteConfig | null> = {}
 
 export async function extractRouteRules (code: string): Promise<NitroRouteConfig | null> {
   if (code in ruleCache) {
-    return ruleCache[code]
+    return ruleCache[code] || null
   }
   if (!ROUTE_RULE_RE.test(code)) { return null }
 
diff --git a/packages/nuxt/src/pages/utils.ts b/packages/nuxt/src/pages/utils.ts
index b45395bde6..e1e14517e9 100644
--- a/packages/nuxt/src/pages/utils.ts
+++ b/packages/nuxt/src/pages/utils.ts
@@ -102,7 +102,7 @@ export function generateRoutesFromFiles (files: ScannedFile[], options: Generate
     // Array where routes should be added, useful when adding child routes
     let parent = routes
 
-    const lastSegment = segments[segments.length - 1]
+    const lastSegment = segments[segments.length - 1]!
     if (lastSegment.endsWith('.server')) {
       segments[segments.length - 1] = lastSegment.replace('.server', '')
       if (options.shouldUseServerComponents) {
@@ -116,7 +116,7 @@ export function generateRoutesFromFiles (files: ScannedFile[], options: Generate
     for (let i = 0; i < segments.length; i++) {
       const segment = segments[i]
 
-      const tokens = parseSegment(segment)
+      const tokens = parseSegment(segment!)
 
       // Skip group segments
       if (tokens.every(token => token.type === SegmentTokenType.group)) {
@@ -151,7 +151,7 @@ export function generateRoutesFromFiles (files: ScannedFile[], options: Generate
 export async function augmentPages (routes: NuxtPage[], vfs: Record<string, string>, augmentedPages = new Set<string>()) {
   for (const route of routes) {
     if (route.file && !augmentedPages.has(route.file)) {
-      const fileContent = route.file in vfs ? vfs[route.file] : fs.readFileSync(await resolvePath(route.file), 'utf-8')
+      const fileContent = route.file in vfs ? vfs[route.file]! : fs.readFileSync(await resolvePath(route.file), 'utf-8')
       const routeMeta = await getRouteMeta(fileContent, route.file)
       if (route.meta) {
         routeMeta.meta = { ...routeMeta.meta, ...route.meta }
@@ -174,7 +174,7 @@ export function extractScriptContent (html: string) {
   for (const match of html.matchAll(SFC_SCRIPT_RE)) {
     if (match?.groups?.content) {
       contents.push({
-        loader: match.groups.attrs.includes('tsx') ? 'tsx' : 'ts',
+        loader: match.groups.attrs?.includes('tsx') ? 'tsx' : 'ts',
         code: match.groups.content.trim(),
       })
     }
@@ -196,7 +196,9 @@ export async function getRouteMeta (contents: string, absolutePath: string): Pro
     delete metaCache[absolutePath]
   }
 
-  if (absolutePath in metaCache) { return metaCache[absolutePath] }
+  if (absolutePath in metaCache && metaCache[absolutePath]) {
+    return metaCache[absolutePath]
+  }
 
   const loader = getLoader(absolutePath)
   const scriptBlocks = !loader ? null : loader === 'vue' ? extractScriptContent(contents) : [{ code: contents, loader }]
@@ -403,7 +405,7 @@ function parseSegment (segment: string) {
             consumeBuffer()
           }
           state = SegmentParserState.initial
-        } else if (PARAM_CHAR_RE.test(c)) {
+        } else if (c && PARAM_CHAR_RE.test(c)) {
           buffer += c
         } else {
           // console.debug(`[pages]Ignored character "${c}" while building param "${buffer}" from "segment"`)
diff --git a/packages/nuxt/test/app.test.ts b/packages/nuxt/test/app.test.ts
index faf40e71be..1bdcb5f8aa 100644
--- a/packages/nuxt/test/app.test.ts
+++ b/packages/nuxt/test/app.test.ts
@@ -297,8 +297,8 @@ async function getResolvedApp (files: Array<string | { name: string, contents: s
     mw.path = normaliseToRepo(mw.path)!
   }
 
-  for (const layout in app.layouts) {
-    app.layouts[layout].file = normaliseToRepo(app.layouts[layout].file)!
+  for (const layout of Object.values(app.layouts)) {
+    layout.file = normaliseToRepo(layout.file)!
   }
 
   await nuxt.close()
diff --git a/packages/nuxt/test/pages.test.ts b/packages/nuxt/test/pages.test.ts
index 3b307387be..f2b2820e81 100644
--- a/packages/nuxt/test/pages.test.ts
+++ b/packages/nuxt/test/pages.test.ts
@@ -653,7 +653,7 @@ describe('pages:generateRoutesFromFiles', () => {
           }))).map((route, index) => {
             return {
               ...route,
-              meta: test.files![index].meta,
+              meta: test.files![index]!.meta,
             }
           })
 
diff --git a/packages/ui-templates/lib/dev.ts b/packages/ui-templates/lib/dev.ts
index 8c2624dbfe..3469dd6257 100644
--- a/packages/ui-templates/lib/dev.ts
+++ b/packages/ui-templates/lib/dev.ts
@@ -31,7 +31,7 @@ export const DevRenderingPlugin = () => {
       const chunks = contents.split(/\{{2,3}[^{}]+\}{2,3}/g)
       let templateString = chunks.shift()
       for (const expression of contents.matchAll(/\{{2,3}([^{}]+)\}{2,3}/g)) {
-        const value = runInNewContext(expression[1].trim(), {
+        const value = runInNewContext(expression[1]!.trim(), {
           version,
           messages: { ...genericMessages, ...messages },
         })
diff --git a/packages/vite/src/manifest.ts b/packages/vite/src/manifest.ts
index 15172431fd..994f1d3f41 100644
--- a/packages/vite/src/manifest.ts
+++ b/packages/vite/src/manifest.ts
@@ -5,11 +5,13 @@ import { relative, resolve } from 'pathe'
 import { withTrailingSlash, withoutLeadingSlash } from 'ufo'
 import escapeRE from 'escape-string-regexp'
 import { normalizeViteManifest } from 'vue-bundle-renderer'
+import type { Manifest as RendererManifest } from 'vue-bundle-renderer'
+import type { Manifest as ViteClientManifest } from 'vite'
 import type { ViteBuildContext } from './vite'
 
 export async function writeManifest (ctx: ViteBuildContext) {
   // This is only used for ssr: false - when ssr is enabled we use vite-node runtime manifest
-  const devClientManifest = {
+  const devClientManifest: RendererManifest = {
     '@vite/client': {
       isEntry: true,
       file: '@vite/client',
@@ -30,17 +32,17 @@ export async function writeManifest (ctx: ViteBuildContext) {
   const serverDist = resolve(ctx.nuxt.options.buildDir, 'dist/server')
 
   const manifestFile = resolve(clientDist, 'manifest.json')
-  const clientManifest = ctx.nuxt.options.dev ? devClientManifest : JSON.parse(readFileSync(manifestFile, 'utf-8'))
+  const clientManifest = ctx.nuxt.options.dev ? devClientManifest : JSON.parse(readFileSync(manifestFile, 'utf-8')) as ViteClientManifest
+  const manifestEntries = Object.values(clientManifest)
 
   const buildAssetsDir = withTrailingSlash(withoutLeadingSlash(ctx.nuxt.options.app.buildAssetsDir))
   const BASE_RE = new RegExp(`^${escapeRE(buildAssetsDir)}`)
 
-  for (const key in clientManifest) {
-    const entry = clientManifest[key]
+  for (const entry of manifestEntries) {
     if (entry.file) {
       entry.file = entry.file.replace(BASE_RE, '')
     }
-    for (const item of ['css', 'assets']) {
+    for (const item of ['css', 'assets'] as const) {
       if (entry[item]) {
         entry[item] = entry[item].map((i: string) => i.replace(BASE_RE, ''))
       }
@@ -50,12 +52,11 @@ export async function writeManifest (ctx: ViteBuildContext) {
   await mkdir(serverDist, { recursive: true })
 
   if (ctx.config.build?.cssCodeSplit === false) {
-    for (const key in clientManifest as Record<string, { file?: string }>) {
-      const val = clientManifest[key]
-      if (val.file?.endsWith('.css')) {
+    for (const entry of manifestEntries) {
+      if (entry.file?.endsWith('.css')) {
         const key = relative(ctx.config.root!, ctx.entry)
-        clientManifest[key].css ||= []
-        clientManifest[key].css!.push(val.file)
+        clientManifest[key]!.css ||= []
+        ;(clientManifest[key]!.css as string[]).push(entry.file)
         break
       }
     }
diff --git a/packages/vite/src/plugins/analyze.ts b/packages/vite/src/plugins/analyze.ts
index edecf536c7..d5e8e4432e 100644
--- a/packages/vite/src/plugins/analyze.ts
+++ b/packages/vite/src/plugins/analyze.ts
@@ -18,8 +18,7 @@ export function analyzePlugin (ctx: ViteBuildContext): Plugin[] {
           const bundle = outputBundle[_bundleId]
           if (!bundle || bundle.type !== 'chunk') { continue }
           const minifiedModuleEntryPromises: Array<Promise<[string, RenderedModule]>> = []
-          for (const moduleId in bundle.modules) {
-            const module = bundle.modules[moduleId]!
+          for (const [moduleId, module] of Object.entries(bundle.modules)) {
             minifiedModuleEntryPromises.push(
               transform(module.code || '', { minify: true })
                 .then(result => [moduleId, { ...module, code: result.code }]),
diff --git a/packages/vite/src/plugins/public-dirs.ts b/packages/vite/src/plugins/public-dirs.ts
index e2765510f5..a1fb15ee24 100644
--- a/packages/vite/src/plugins/public-dirs.ts
+++ b/packages/vite/src/plugins/public-dirs.ts
@@ -86,8 +86,7 @@ export const VitePublicDirsPlugin = createUnplugin((options: VitePublicDirsPlugi
           }
         },
         generateBundle (_outputOptions, bundle) {
-          for (const file in bundle) {
-            const chunk = bundle[file]!
+          for (const [file, chunk] of Object.entries(bundle)) {
             if (!file.endsWith('.css') || chunk.type !== 'asset') { continue }
 
             let css = chunk.source.toString()
diff --git a/packages/vite/src/plugins/ssr-styles.ts b/packages/vite/src/plugins/ssr-styles.ts
index c7c83a3439..345cf96a09 100644
--- a/packages/vite/src/plugins/ssr-styles.ts
+++ b/packages/vite/src/plugins/ssr-styles.ts
@@ -62,8 +62,7 @@ export function ssrStylesPlugin (options: SSRStylePluginOptions): Plugin {
       if (options.mode === 'client') { return }
 
       const emitted: Record<string, string> = {}
-      for (const file in cssMap) {
-        const { files, inBundle } = cssMap[file]!
+      for (const [file, { files, inBundle }] of Object.entries(cssMap)) {
         // File has been tree-shaken out of build (or there are no styles to inline)
         if (!files.length || !inBundle) { continue }
         const fileName = filename(file)
diff --git a/packages/vite/src/vite.ts b/packages/vite/src/vite.ts
index 7b51573d10..856be03fa6 100644
--- a/packages/vite/src/vite.ts
+++ b/packages/vite/src/vite.ts
@@ -207,8 +207,7 @@ export const bundle: NuxtBuilder['bundle'] = async (nuxt) => {
 
     // Remove CSS entries for files that will have inlined styles
     ctx.nuxt.hook('build:manifest', (manifest) => {
-      for (const key in manifest) {
-        const entry = manifest[key]!
+      for (const [key, entry] of Object.entries(manifest)) {
         const shouldRemoveCSS = chunksWithInlinedCSS.has(key) && !entry.isEntry
         if (entry.isEntry && chunksWithInlinedCSS.has(key)) {
           // @ts-expect-error internal key
diff --git a/packages/webpack/src/plugins/vue/client.ts b/packages/webpack/src/plugins/vue/client.ts
index 23259c6cba..005afcf18e 100644
--- a/packages/webpack/src/plugins/vue/client.ts
+++ b/packages/webpack/src/plugins/vue/client.ts
@@ -33,9 +33,10 @@ export default class VueSSRClientPlugin {
       const stats = compilation.getStats().toJson()
 
       const initialFiles = new Set<string>()
-      for (const name in stats.entrypoints!) {
-        const entryAssets = stats.entrypoints![name]!.assets!
-        for (const asset of entryAssets) {
+      for (const { assets } of Object.values(stats.entrypoints!)) {
+        if (!assets) { continue }
+
+        for (const asset of assets) {
           const file = asset.name
           if ((isJS(file) || isCSS(file)) && !isHotUpdate(file)) {
             initialFiles.add(file)
@@ -71,52 +72,53 @@ export default class VueSSRClientPlugin {
       }
 
       const { entrypoints = {}, namedChunkGroups = {} } = stats
-      const assetModules = stats.modules!.filter(m => m.assets!.length)
-      const fileToIndex = (file: string) => webpackManifest.all.indexOf(file)
-      stats.modules!.forEach((m) => {
+      const fileToIndex = (file: string | number) => webpackManifest.all.indexOf(String(file))
+      for (const m of stats.modules!) {
         // Ignore modules duplicated in multiple chunks
-        if (m.chunks!.length === 1) {
-          const [cid] = m.chunks!
-          const chunk = stats.chunks!.find(c => c.id === cid)
-          if (!chunk || !chunk.files || !cid) {
-            return
-          }
-          const id = m.identifier!.replace(/\s\w+$/, '') // remove appended hash
-          const filesSet = new Set(chunk.files.map(fileToIndex).filter(i => i !== -1))
+        if (m.chunks?.length !== 1) { continue }
 
-          for (const chunkName of chunk.names!) {
-            if (!entrypoints[chunkName]) {
-              const chunkGroup = namedChunkGroups[chunkName]
-              if (chunkGroup) {
-                for (const asset of chunkGroup.assets!) {
-                  filesSet.add(fileToIndex(asset.name))
-                }
-              }
-            }
-          }
-
-          const files = Array.from(filesSet)
-          webpackManifest.modules[hash(id)] = files
-
-          // In production mode, modules may be concatenated by scope hoisting
-          // Include ConcatenatedModule for not losing module-component mapping
-          if (Array.isArray(m.modules)) {
-            for (const concatenatedModule of m.modules) {
-              const id = hash(concatenatedModule.identifier!.replace(/\s\w+$/, ''))
-              if (!webpackManifest.modules[id]) {
-                webpackManifest.modules[id] = files
-              }
-            }
-          }
-
-          // Find all asset modules associated with the same chunk
-          assetModules.forEach((m) => {
-            if (m.chunks!.includes(cid)) {
-              files.push(...(m.assets as string[]).map(fileToIndex))
-            }
-          })
+        const [cid] = m.chunks
+        const chunk = stats.chunks!.find(c => c.id === cid)
+        if (!chunk || !chunk.files || !cid) {
+          continue
         }
-      })
+        const id = m.identifier!.replace(/\s\w+$/, '') // remove appended hash
+        const filesSet = new Set(chunk.files.map(fileToIndex).filter(i => i !== -1))
+
+        for (const chunkName of chunk.names!) {
+          if (!entrypoints[chunkName]) {
+            const chunkGroup = namedChunkGroups[chunkName]
+            if (chunkGroup) {
+              for (const asset of chunkGroup.assets!) {
+                filesSet.add(fileToIndex(asset.name))
+              }
+            }
+          }
+        }
+
+        const files = Array.from(filesSet)
+        webpackManifest.modules[hash(id)] = files
+
+        // In production mode, modules may be concatenated by scope hoisting
+        // Include ConcatenatedModule for not losing module-component mapping
+        if (Array.isArray(m.modules)) {
+          for (const concatenatedModule of m.modules) {
+            const id = hash(concatenatedModule.identifier!.replace(/\s\w+$/, ''))
+            if (!webpackManifest.modules[id]) {
+              webpackManifest.modules[id] = files
+            }
+          }
+        }
+
+        // Find all asset modules associated with the same chunk
+        if (stats.modules) {
+          for (const m of stats.modules) {
+            if (m.assets?.length && m.chunks?.includes(cid)) {
+              files.push(...m.assets.map(fileToIndex))
+            }
+          }
+        }
+      }
 
       const manifest = normalizeWebpackManifest(webpackManifest as any)
       await this.options.nuxt.callHook('build:manifest', manifest)
diff --git a/test/bundle.test.ts b/test/bundle.test.ts
index 96d480afc3..ec4dc393f6 100644
--- a/test/bundle.test.ts
+++ b/test/bundle.test.ts
@@ -18,13 +18,13 @@ describe.skipIf(process.env.SKIP_BUNDLE_SIZE === 'true' || process.env.ECOSYSTEM
   // Identical behaviour between inline/external vue options as this should only affect the server build
 
   it('default client bundle size', async () => {
-    const [clientStats, clientStatsInlined] = await Promise.all(['.output', '.output-inline']
+    const [clientStats, clientStatsInlined] = await Promise.all((['.output', '.output-inline'])
       .map(outputDir => analyzeSizes(['**/*.js'], join(rootDir, outputDir, 'public'))))
 
-    expect.soft(roundToKilobytes(clientStats.totalBytes)).toMatchInlineSnapshot(`"114k"`)
-    expect.soft(roundToKilobytes(clientStatsInlined.totalBytes)).toMatchInlineSnapshot(`"114k"`)
+    expect.soft(roundToKilobytes(clientStats!.totalBytes)).toMatchInlineSnapshot(`"114k"`)
+    expect.soft(roundToKilobytes(clientStatsInlined!.totalBytes)).toMatchInlineSnapshot(`"114k"`)
 
-    const files = new Set([...clientStats.files, ...clientStatsInlined.files].map(f => f.replace(/\..*\.js/, '.js')))
+    const files = new Set([...clientStats!.files, ...clientStatsInlined!.files].map(f => f.replace(/\..*\.js/, '.js')))
 
     expect([...files]).toMatchInlineSnapshot(`
       [
diff --git a/tsconfig.json b/tsconfig.json
index c912996aa5..6763732a3f 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -12,8 +12,7 @@
     "verbatimModuleSyntax": true,
     /* Strictness */
     "strict": true,
-    // TODO: enable noUncheckedIndexedAccess
-    // "noUncheckedIndexedAccess": true,
+    "noUncheckedIndexedAccess": true,
     "noUncheckedSideEffectImports": true,
     "forceConsistentCasingInFileNames": true,
     "noImplicitOverride": true,