Set up appropriate error handlers so db server doesn't crash

[patudom]

Per our team meeting, we've seen that insufficient error handling can cause local instances of a db server to crash. We need to ensure that this doesn't happen to the deployed server with live students.

[Carifio24]

I added some extra error handling in #141, as well as a linting rule that should help quite a bit, but I'm going to keep this open and continue until we have some testing set up (which I'm working on) so that we can really be sure that the server won't ever crash.