In dev (FLASK_DEBUG=true), showing a traceback is good. If we are not in dev, we currently show a 500 internal server error page.

To do better than that, we should show something to the user that is useful for reporting the error ("who do I call?"), describes how to recover, and enables them to continue using the app.

We should set this up so all exceptions generated by requests are caught. Does Flask have a built-in method to intercept request exceptions?

Probably a medium-term thing?