Seppuku

Track error occurrences and shutdown service instance once a defined number of unique messages have errors in a defined time period.
actually, does it have to be a hash? Couldn't it just be an Array of Arrays: `[[sha, expiration],...]`. It would in theory be faster than a hash for the types of operations. Do we care that they're unique errors or could we be more general and say 20 errors in 5 minutes or something like that? Perhaps this is something we have to iterate on to find the right result?