dillon1000/react

[Fiber] New error boundary semantics (#8304)

* Exit early in scheduleUpdate if a node's priority matches

This is a performance optimization and is unobservable. However, it
helps protect against regressions on the following invariants on which
it relies:

- The priority of a fiber is greater than or equal to the priority of
all its descendent fibers.
- If a tree has pending work priority, its root is scheduled.

* New error boundary semantics

- Recovering from an error boundary no longer uses Task priority by
default. The work is scheduled using whatever priority created the
error.
- Error handling is now a side-effect that happens during the
commit phase.
- The default behavior of an error boundary is to render null. Errors
do not propagate except when an boundary fails. Conceptually, this would
be like throwing an error from a catch block.
- A host container is treated like a no-op error boundary. The first
error captured by a host container is thrown at the end of the batch.
Like with normal error boundaries, the entire tree is unmounted.

* Fix broken setState callback test

* Add test for "unwinding" context when an error interrupts rendering

* Switch over primary effect types only

This avoids the need to create an export for every combination of bits.

* Only continue the work loop if the error was successfully captured

* Add more tests for incremental error handling

These tests are currently failing:

  ✕ catches render error in a boundary during partial deferred mounting
  ✕ catches render error in a boundary during animation mounting
  ✕ propagates an error from a noop error boundary during full deferred mounting
  ✕ propagates an error from a noop error boundary during partial deferred mounting
  ✕ propagates an error from a noop error boundary during animation mounting

The observed behavior is that unstable_handleError() unexpected gets called twice:

      "ErrorBoundary render success",
      "BrokenRender",
      "ErrorBoundary unstable_handleError",
  +   "ErrorBoundary render success",
  +   "BrokenRender",
  +   "ErrorBoundary unstable_handleError",
      "ErrorBoundary render error"

* Verify batched updates get scheduled despite errors

* Add try/catch/finally blocks around commit phase passes

We'll consolidate all these blocks in a future PR that refactors the
commit phase to be separate from the perform work loop.

* NoopBoundary -> RethrowBoundary

* Only throw uncaught error once there is no more work to perform

* Remove outdated comment

It was fixed in #8451.

* Record tests

* Always reset nextUnitOfWork on error

This is important so that the test at the end of performAndHandleErrors() knows it's safe to rethrow.

* Add a passing test for unmounting behavior on crashed tree

* Top-level errors

An error thrown from a host container should be "captured" by the host
container itself

* Remove outdated comment

* Separate Rethrow and Noop scenarios in boundary tests

* Move try block outside the commit loops