Crash reporting & alerting for DevTools

_This is an action item from the postmortem review for https://github.com/flutter/devtools/issues/9701_

The "memory access out of bounds" error described in https://github.com/flutter/devtools/issues/9701 was never sent to our analytics, therefore we had no visibility into these failures.

This issue tracks:

1. Investigation work into why these errors were not being reported
2. Whatever work is necessary to have them reported, determine their severity, and send alerts based on the severity

Start by reading the postmortem issue #9701 and trace how the described "memory access out of bounds" error currently reaches analytics. Identify the existing reporting and alerting entry points, then determine how severity should be represented. Done means these failures are reported and alerts are sent according to their severity.

索引モデルが issue の本文から書いたものです。