SERVER-94231 changed query stats key generation to catch all errors and propagate them only if internalQueryStatsErrorsAreCommandFatal is enabled. This ended up causing some interesting test failures due to some queries that end in error seeing that error for the first time during query stats key generation (rather than at parse time). See this comment for more context. These failures are likely due to serialize() implementations having side effects (additional validation most likely) - SERVER-94818 is one example.
To prevent fatal failures in evergreen, we have changed the query stats tassert to a uassert. We should try changing it back to a tassert and audit the resulting test failures to see if there are any other cases that should be fixed.

Note: resmoke didn't seem to have an issue with tasserts when running locally, but fixture clean-up tasks in evergreen did. Some extra care might need to be taken to check for these failures when running locally (or maybe just use invariant instead).