next.js

a8e01141 - [unstable_after] fix occasional dev-mode crash in edge runtime pages (#66099)

[unstable_after] fix occasional dev-mode crash in edge runtime pages (#66099) When hot-reloading an edge runtime page, sometimes we randomly get this: ``` [InvariantError: Invariant: Cannot call onClose on a response that is already sent. This is a bug in Next.js.] { name: 'InvariantError' } ``` and since `unstable_after` relies on `onClose`, no callbacks are called. I believe this is because `web-server` [calls `res.send()` pretty early for streaming responses](https://github.com/vercel/next.js/blob/b9817f83519fdaa7a7fcd4711dfb80aa1e1a2434/packages/next/src/server/web-server.ts#L311), so `res.sent` becomes `true` even though we're still streaming, and prevents us from calling `onClose` in the streaming render. It makes more sense to check the CloseController's `isClosed` instead -- when that becomes `true`, we _really_ shouldn't call onClose anymore (points to a bug), but before that it's fine.