The /summary command is currently not performing any validation on the input. This makes it possible for a user to either mistakenly or willingly enter a bad summary that will cause CheckRuns to fail with exceptions when parsing the commit message. Once in this state, there is currently no way for the PR bot to recover. (Clearing the summary with an empty /summary command doesn't work, because the bot wants to run CheckWorkItem first, which is failing)

I would like to fix this in two ways:

1. Add validation to the SummaryCommand that makes sure the resulting commit comment is valid and produces a suitable error message otherwise. It should also check for obvious things that aren't a "summary" message, like "Reviewed-by:" or "<bugid>:".

2. Handle a bad commit message better without throwing exception. If the commit message is invalid, I think this should be treated as an integration blocker instead.