fix(nuxt): manually assign payload reactivity when ssr: false (#27542)

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

@@ -3,6 +3,7 @@ import { parse } from 'devalue'
 import { useHead } from '@unhead/vue'
 import { getCurrentInstance, onServerPrefetch } from 'vue'
 import { useNuxtApp, useRuntimeConfig } from '../nuxt'
+import type { NuxtPayload } from '../nuxt'
 
 import { useRoute } from './router'
 import { getAppManifest, getRouteRules } from './manifest'
@@ -95,11 +96,12 @@ export async function isPrerendered (url = useRoute().path) {
   return !!rules.prerender && !rules.redirect
 }
 
-let payloadCache: any = null
+let payloadCache: NuxtPayload | null = null
+
 /** @since 3.4.0 */
 export async function getNuxtClientPayload () {
   if (import.meta.server) {
-    return
+    return null
   }
   if (payloadCache) {
     return payloadCache
@@ -107,7 +109,7 @@ export async function getNuxtClientPayload () {
 
   const el = document.getElementById('__NUXT_DATA__')
   if (!el) {
-    return {}
+    return {} as Partial<NuxtPayload>
   }
 
   const inlineData = await parsePayload(el.textContent || '')

packages/nuxt/src/app/nuxt.ts

@@ -69,7 +69,7 @@ export interface NuxtSSRContext extends SSRContext {
   /** whether we are rendering an SSR error */
   error?: boolean
   nuxt: _NuxtApp
-  payload: NuxtPayload
+  payload: Partial<NuxtPayload>
   head: VueHeadClient<MergeHead>
   /** This is used solely to render runtime config with SPA renderer. */
   config?: Pick<RuntimeConfig, 'public' | 'app'>

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

@@ -165,11 +165,7 @@ const getSPARenderer = lazyCachedFunction(async () => {
     const config = useRuntimeConfig(ssrContext.event)
     ssrContext.modules = ssrContext.modules || new Set<string>()
     ssrContext!.payload = {
-      _errors: {},
       serverRendered: false,
-      data: {},
-      state: {},
-      once: new Set<string>(),
     }
     ssrContext.config = {
       public: config.public,