Is this one of the dub hello worlds? Looks like it.... but it also says line 8 and the built in thing doesn't have a line 8. So what is the code there? If it is `assert(0)`, you're seeing the result of the test. The info is a bit spammy since it prints all the mostly-useless stack trace but there's some situations beyond hello world where the extra info helps explain why the test failed.