[DISCUSSION] Carry out a sentry exception triage, and create guidance on sampling

[mrchrisadams]

We have a number of exceptions in Sentry now, and while some are really important, others are much less so.

It would really help to triage what we have so we can establish some rules for ignoring unimportant ones, and only have a list of the ones we really intend to act on.

Elsewhere where there are exceptions that do we want to track, to prevent us burning through our quota each month, it's worth seeing if any of sentry's logic would help us catch errors we want to see on the services and routes that receive a lot of traffic.

Having some rules of thumb documented, as well as guidance on how to do this would be very helpful.