Check error handling is fit for purpose for AMS

[tofu-rocketry]

It may be necessary to catch IOError in addition to OSError in on_message as there is no real difference between them and we sometimes get the former being raised, but we need to sort out how we acknowledge messages we pull from AMS otherwise we end up in a loop of continually trying to pull down the same message.

This issue was fixed for the original style of messaging in #63 but didn't get carried over for AMS messaging. (There's a large section that should be factored out for both types of messaging to avoid issues like this!)

Should also rename error to e to match on_message convention to simplify refactoring later.

[tofu-rocketry]

Seems to have been superseded by the refactoring.