Handle sync validations

[DaddyWarbucks]

Solves: #2052

[jquense]

Suggested change

	if (!options.sync) {
	return Promise.resolve(result).then(
	handleResult,
	handleError,
	);
	}
	if (options.sync)
	throw Error(...)
	return result.then(
	handleResult,
	handleError,
	);

I think this is all you actually need here? the sync check now only serves to throw if there is a promise when there shouldn't be

[jquense]

SGTM, trying to think if there are potential race conditions now...there shouldn't be, or at least if their are they also affect the explicit sync pathway as well.

this is a little Zalgo-y but i think it's probably worth it...

[DaddyWarbucks]

@jquense I spun up this little repo as a test bed: https://github.com/DaddyWarbucks/yup-sync-validation

I roughly estimated the schema to have about 100 validation tests per data from the repo. Given every property has multiple tests, I just rounded to 100 for the statements below.

validateSync.loop and validateAsync.loop are interesting because they have similar performance. On every iteration of the validateAsync.loop 100 promises are pushed/popped off the event loop at a time. So the event loop doesn't cough on that.

The problem seems to present itself when using promise.all and promise.allSettled because the event loop is overloaded with 1 million+ promises at once. The new approach improves that by only applying true async tests to the event loop.