make the bot render errors, aware of the big error families

Some errors:

* audit failed (normal, triggers our webapp)
* violation conflict (you have audits/exemptions that contradict the violations, not currently in scope for the webapp)
* currently this error is a bit late-bound, because it only triggers if you have assertions that *contradict* exemptions
* because it's technically fine to have a dev-dep which is known not-safe-to-deploy!
* I don't think we have safe-guards against recommending audits that contradict known violations :(
* technically this is actually difficult for the CI to do (#22)
* integrity errors
* hey your file refers an undefined criteria (just print the string, more or less)

Start by locating the bot's error-rendering path and the handlers for audit, violation-conflict, and integrity errors. Read issue #22 for the CI context, then define completion as rendering each error family with the distinctions and undefined-criteria message described here.

Written by the indexing model from the issue text.