fix: build hangs if sync IO aborts before root chunk is flushed (#94365)
Mitigates a regression introduced in
https://github.com/vercel/next.js/pull/94044. We switched from prerender
to render + cutting of chunks that are emitted after abort. This works
well for the abort we trigger to finish prerendering, because we ensure
that everything that was going to flush some output already did so
before we abort.
However, when Sync IO causes an abrupt abort in the middle of rendering,
we also have to stop collecting output immediately (because e.g. async
iterables are errored ~immediately, without `scheduleWork`), which means
that partially-finished chunks may get omitted from the output.
Essentially, when Sync IO happens, we might lose more content that we
would've if we did a halt.
In the the pages in the test suite added here, the root chunk (row 0)
ends up being blocked. Before the fix introduced in this PR, this bad
RSC payload would then flow into `collect-segment-data.ts` which
attempts to deserialize it and hangs in an unexpected way (because with
a halt, the root chunk was always there).
I've also had to add a weird workaround to the streaming prerender
codepaths -- it seems like in --debug-prerender, the stale time iterable
keeps the stream open even after an abort, and we need to close it
manually (which seems like a react bug). See NAR-810
next.js
006096cb - fix: build hangs if sync IO aborts before root chunk is flushed (#94365)
