Communicate empty stack trace on error page in frontend

We should communicate better when an error has an empty stack trace.

Currently the error page just doesn't render the stack trace if it's empty:

Some suggestions (from #119205 (comment 267694717)):

So my question was do we want to communicate this to the user, maybe with "No stacktrace for this error" or something similar.

I like this suggestion! I suppose the simplest way to communicate this message would be to use the blue information alert, as what we're communicating isn't necessarily a problem, it's just offering users some additional information. In the longer term, we could perhaps craft an empty state for the stack trace directly in the UI, but that would require a little more design work.