Internal errors should not occur but sadly they do.
Most times these are errors that we should have converted to JS exceptions but just didn't other times it's something that actually went really badly in the runtime.
Best way to work around them or understand them is to get them to reproduce in local dev. Then a github issue with the reproducer is usually enough for us to quickly squash the error or at least convert it to an understandable JS exception.
Reproducing in local dev should also make it easier to pinpoint the error location.
Sadly that's the best we've got at the minute.
We've got a project going to attach an "id" to each internal error so that we could quickly find it in our logs and provide you with a better answer of what caused it. I think it should be available rather soon.
