if uncaughtExceptionMonitor handler throws, the process dies without chance for recovery by uncaughtException or uncaughtRejection

[MadaraUchiha]

• Version: v15.14.0
• Platform: all
• Subsystem: process/execution

What steps will reproduce the bug?

1. Register an uncaughtExceptionMonitor handler on process, which itself throws
2. Throw an error without catching it

How often does it reproduce? Is there a required condition?

Every time.

What is the expected behavior?

uncaughtException event on process to be fired, if error is handled don't crash the process.

• Ideally with an AggregateError containing both errors
• But at least with the original error

What do you see instead?

The process simply dies with error code 7. uncaughtException isn't emitted.

Additional information

Example file:

process.addListener('uncaughtExceptionMonitor', (e) => {
  console.error('Monitored Error!', e);
  throw new Error('Oopsie!');

});

process.addListener('uncaughtException', e => {
  console.error('Handled error!', e);
})
let i = 0;
setInterval(() => console.log(i++), 1000);
throw new Error('Thrown!');

Expected

Monitored: ...
Handled: ...
0
1
2
...

Actual

Monitored: ...
/path/to/test.js:3
  throw new Error('Oopsie!');
  ^

Error: Oopsite!
    at ...

$ # process died, error code is 7

[MadaraUchiha]

I am working on a PR for this, to be submitted in the near future.

[benjamingr]

I'm not sure this is not by design @nodejs/post-mortem

[Linkgoron]

I'm not sure this is not by design @nodejs/post-mortem

#31257 (comment)

There was some discussion around it, but maybe now that AggregateError exists, there are other options.

[MadaraUchiha]

Additionally, today, the process exits with error code 7 (which is different from the normal 1 of an uncaught exception that the uncaughtException handler declined to handle).

I believe this behavior should be preserved, since it's an outwards facing API that's enforced by an existing test. See https://github.com/nodejs/node/blob/master/test/parallel/test-process-uncaught-exception-monitor.js#L32.

WDYT?