Coverage increased (+0.002%) to 99.807% when pulling 69cc710 on fix/effect-error into ec5340f on master.

oh snap, thanks, was gonna clone after lunch 😉

does it make sense to catch in _render, unmount, etc too?

No, those are part of the diffing algorithm it are only the ones scheduled for delayed execution that bypass diff and don't get picked up by the parentComponents.

Seems like I didn't press enter when commenting on your issue, sorry for that.

ahh. if you get a chance can you link to where that happens?

I can surely do so

For the first case we do a synchronous cleanup for the effects still pending for a component this can happen with many subsequent renders, here we use the _render option this is within the diffing loop so if a throw occurs it will catch it just as a normal throw in render would.

For the next case we have unmount, something that can only occur during diffing when we are diffing children and we see that one isn't there anymore we call unmount which links through to the option we are still in our diffing loop since diffChildren is called from the regular diff so if it happens to throw we'll and up in the same catch as the one mentioned above.

ah ok, so then diffed is just a callback to be executed when the diffing is done?

One last scenario is throwing in useLayoutEffect this can error out because we are reusing the commitQueue with objects (x._value()) instead of x(). So if a useLayoutEffectt throws that is not removed from the commitQueue and will just run the commitQueue afterwards (since this is part of the options hook)

This PR: #2203 can solve that more easily

@robertknight with the new changes in this PR errors in _commit will be caught. Just checked with @JoviDeCroock regarding _render and imo it's "edge-casy" enough that we can move that to another PR. We only flush effects there on synchronous rendering. Example from our test suite:

it('works with closure effect callbacks capturing props', () => {
  const values = [];

  function Comp(props) {
    useEffect(() => values.push(props.value));
    return null;
  }

  render(<Comp value={1} />, scratch);
  render(<Comp value={2} />, scratch);
  return scheduleEffectAssert(() => expect(values).to.deep.equal([1, 2]));
);