Narrow our exceptions

[seisatsu]

For everywhere possible, change broad exception clauses to list the particular exceptions to be expected.

[pmer]

I've no idea how this will impact the stability of the engine... but some exceptions mean our internal state is messed up somehow and we can't recover. We can't always be perfect. I'm looking forward to seeing how we fare with this strategy.

[pmer]

Ah, looks like except Exception will allow SystemExit, KeyboardInterrupt, and GeneratorExit to pass through uncaught.

Just saw https://docs.python.org/3/library/exceptions.html#exception-hierarchy

[seisatsu]

Well that's a dealbreaker. We'll just deal with this issue later. I've moved us back to old exceptions for now.