V5: error handling for actions

[christophe-g]

I am not sure if this need to be reported as a bug, but I am having issues with how to handle unhandled errors in actions (works well with actor logic like fromPromise, ...).

I am expecting 2 things from the following scenario:

1. the unhandled_sync_error_on_state_entry error is caught on actorRef.subscribe({error: ...}), and
2. the latest snapshot is in an error status.

1. is satisfied in my local tests, but not 2. (status is active)

const machine = createMachine({
      initial: 'pending',
      states: {
        pending: {
          entry: () => {
            throw new Error('unhandled_sync_error_on_state_entry');
          }
        }
      }
    });

    const actorRef = createActor(machine);
    actorRef.subscribe({
      error: (error) => {
       // the error 'unhandled_sync_error_on_state_entry' sync error is caught here
      }
    });
    actorRef.start();
    // actorRef.getSnapshot().status is error

I tried to add this test in the error test suite as I think this should be the expected behavior, but it fails (just note that I am new to xstate and might miss smth very stupid, so bear with me !)

  it(`unhandled sync errors thrown on state entry should crash the parent`, (done) => {
    const machine = createMachine({
      initial: 'pending',
      states: {
        pending: {
          entry: () => {
            throw new Error('unhandled_sync_error_on_state_entry');
          }
        }
      }
    });

    const actorRef = createActor(machine);
    actorRef.subscribe({
      error: (error) => {
        expect((error as Error).message).toBe('unhandled_sync_error_on_state_entry');
        // error is caught here, we throw for upstream (global)
        throw new Error('unhandled_sync_error_on_state_entry_global');
      }
    });
    actorRef.start();

    expect(actorRef.getSnapshot().status).toBe('error');

    installGlobalOnErrorHandler((ev) => {
      ev.preventDefault();
      expect(ev.error.message).toEqual('unhandled_sync_error_on_state_entry_global');
      done();
    });
  });

[Andarist]

I think that this open PR resolves both of your concerns: #4492 . Could you recheck your expectations with its content?

[christophe-g]

Haha - you are brilliant

The above test pass when checked-out from #4492 !

Thanks - I'll just wait for the PR to be merged.