Get error handling more normalized with custom exceptions and so forth

[emersonrp]

I've just started the notion of custom exceptions in BindFile, but really there's a lot of places that we could use that pattern instead of just "except Exception as e" and throw some sort of ugly error message.

ruff "TRY" rules can steer this a bit.

This wants to be its own separate project.

[emersonrp]

Working on this in the branch more_exceptions. Not clear whether this is a win yet.