fix: request APIs in promises passed to after() in actions/handlers (#94964)
Fixes a bug where Route Handlers and Server Actions were prevented from
calling `headers()` (and other request APIs) if
- the call happened after the response is finished
- the call *did not happen* inside an after-callback
generally, this happens when you pass a promise to after.
```ts
const longRunning = () => {
// assume this resolves after the response
await new Promise((resolve) => setTimeout(resolve, 100))
// response is done
after(() => {
await headers() // ❌ should be allowed, but throws
})
}
after(longRunning()) // or waitUntil, doesn't matter
```
The logic we used in the check was incorrect and assumed that an
`afterTaskStore` was present, but we can only wrap callbacks in this ALS
- we cannot change the async context of already-running promises.
One noteworthy change is that i had to exit `actionAsyncStorage` when we
do a render after the server action. Otherwise the checks in
`isRequestApiAllowedInCurrentPhase` might believe that they're still in
a server action when they aren't.
next.js
7fc1a200 - fix: request APIs in promises passed to after() in actions/handlers (#94964)
