fix: throw when a store is used outside of a Nuxt-aware context.

packages/nuxt/global.d.ts

@@ -0,0 +1,2 @@
+// Global compile-time constants
+declare var __TEST__: boolean

packages/nuxt/playground/pages/usage-after-await.vue

@@ -0,0 +1,24 @@
+<script lang="ts" setup>
+async function useFancyCounter() {
+  await new Promise((resolve) => setTimeout(resolve, 0))
+
+  // ❌ bad usage: the use of a store after an await could lead to using the wrong pinia instance.
+  return useCounter()
+}
+
+const event = useRequestEvent()
+useNuxtApp().hook('vue:error', (error) => {
+  if (event) {
+    setResponseStatus(event, 500, String(error))
+  }
+})
+
+const counter = await useFancyCounter()
+</script>
+
+<template>
+  <div>
+    <p>Count: {{ counter.$state.count }}</p>
+    <button @click="counter.increment()">+</button>
+  </div>
+</template>

packages/nuxt/src/runtime/composables.ts

@@ -1,5 +1,33 @@
 import { useNuxtApp } from '#app'
-import type { Pinia } from 'pinia'
+import {
+  defineStore as _defineStore,
+  type Pinia,
+  type StoreGeneric,
+} from 'pinia'
 export * from 'pinia'
 
-export const usePinia = () => useNuxtApp().$pinia as Pinia
+export const usePinia = () => useNuxtApp().$pinia as Pinia | undefined
+
+export const defineStore: typeof _defineStore =
+  process.env.NODE_ENV === 'production' && !__TEST__
+    ? _defineStore
+    : (((
+        ...args: Parameters<typeof _defineStore>
+      ): ReturnType<typeof _defineStore> => {
+        if (!import.meta.server) {
+          return _defineStore(...args)
+        }
+
+        const originalUseStore = _defineStore(...args)
+        function useStore(
+          pinia?: Pinia | null,
+          hot?: StoreGeneric
+        ): StoreGeneric {
+          return originalUseStore(pinia || usePinia(), hot)
+        }
+
+        useStore.$id = originalUseStore.$id
+        useStore._pinia = originalUseStore._pinia
+
+        return useStore
+      }) as typeof _defineStore)

packages/nuxt/test/nuxt.spec.ts

@@ -37,4 +37,10 @@ describe('Nuxt', async () => {
   it('can auto import from layers', async () => {
     expect(await $fetch('/')).toContain('Layer store: 0')
   })
+
+  it('throws an error server-side when the nuxt context is not available', async () => {
+    await expect($fetch('/usage-after-await')).rejects.toThrowError(
+      '[nuxt] instance unavailable'
+    )
+  })
 })

packages/nuxt/tsconfig.json

@@ -2,6 +2,7 @@
   "extends": "./playground/.nuxt/tsconfig.json",
   "include": [
     "./shims.d.ts",
+    "./global.d.ts",
     // missing in the playground
     "./src"
   ]