Without this, the exception trace is pretty useless, because it only includes Loop::run() and other internal loop calls, giving absolutely no indication which kind of thing had a timeout.
Use debug_backtrace instead of creating the exception early, because it helps with the changes to GC behavior such a change might introduce.
Co-authored-by: Aaron Piotrowski <aaron@trowski.com>
This has been an edge case potentially hiding some exceptions. The tests have been refactored to error if the loop has watchers leaking from one test to another test.
