Consider adding "crashed" test result status

Perhaps there should be a crashed test result status. Perhaps not.

Pros:
* Easily to see that a test result ended with an unexpected error

Cons:
* Is this the right place to have this level of concern? Is a `Failure` not anything that was attempted and not `Passed`?

No file, test, or entry point is named. Start by locating the existing test-result status definition and the places that display or consume it, then review how unexpected errors are currently represented. Done requires a decided status model, agreement on whether crashed is distinct from Failure, and coverage for the chosen behavior.

Written by the indexing model from the issue text.