[tialaramex]

No, you are not guaranteed a stack trace, in an optimised release build it may not even be possible to construct a valid trace. If you can reproduce the problem you can say you want this run to have a stack trace, but if your release builds just exit immediately on panic then there's no reason for them to be able to provide a stack trace of the fault.

On the other hand expect will provoke the message you wrote if it fails. Of course if it's inside a consumer's fitness tracker it probably doesn't have any way to show the message to a human, but that's a different problem - the fitness tracker presumably can't display stack traces either.