feat: add option for ignoring unhandled errors

[DerYeger]

I recently migrated a large project from Jest to Vitest.
During the migration, I encountered issues with unhandled errors due to race conditions (caused by poor tests that don't clean up their async React hooks).

Since there's a huge number of tests, without any way of knowing which tests cause these issues, I had to use patch-package to prevent Vitest from failing due to unhandled errors.

I am aware that this isn't the proper way, but there was no other way of getting around this issue.

With this PR, I propose a new config option for ignoring unhandled errors.
It's fittingly labelled dangerouslyIgnoreUnhandledErrors.

[sheremet-va]

I would much prefer if we could provide a better way of displaying errors to help users find the issues, instead of ignoring it.

[DerYeger]

I would much prefer if we could provide a better way of displaying errors to help users find the issues, instead of ignoring it.

While I agree, I'm not sure if much can be done about improving the reports of unhandled errors.
I'd be happy to work on a solution if someone has an idea.

With the proposed option enabled, Vitest's behaviour would match the behaviour of older Jest versions, making iterative migration much simpler.

[antfu]

Or maybe we could return a different exitCode so you could ignore it with a UNIX pipe or some ci config?

[DerYeger]

Or maybe we could return a different exitCode so you could ignore it with a UNIX pipe or some ci config?

I guess that would work as well (if actually failing tests in presence of unhandled errors still result in exit code 1).

Though it would also have downsides compared to the config option (no central config, no platform independence, can't call package script differently like nr test --no-ui).

[antfu]

I am fine with adding the option, since we have the --dangerously prefix