async_hooks: clear context frame for thrown microtasks

[mcollina]

This clears the AsyncContextFrame before rethrowing exceptions from queueMicrotask() callbacks.

V8 restores continuation-preserved embedder data for microtasks. If a microtask callback throws, exception reporting can re-enter JavaScript while the microtask's context frame is still current. Clearing the frame before rethrowing keeps subsequent exception formatting and microtasks from observing the throwing callback's AsyncLocalStorage state.

Includes a regression test covering a non-Error object thrown from a microtask whose string conversion queues another microtask.

[mcollina]

cc @nodejs/diagnostics

[Qard]

Don't we generally want the context to be available in uncaughtException? We did a bunch of work at one point to ensure it would be there so uncaughtException handlers could attribute the errors to spans they came from in tracers. It'd probably be more correct to cut off the context after those handlers run. 🤔

[mcollina]

Don't we generally want the context to be available in uncaughtException?

I thought as well.

The key assertion here is this one: https://github.com/nodejs/node/pull/64147/changes#diff-6c14bb576b8a1eaf12aeb421aec5efd35b58d92c8a02d668a83a2f74f9c6474fR18.

[mcollina]

Note that if we think the current behavior is correct, then I'll add a test for it to match.