We already surface errors in $queryStats on the creation of the key as a uassert rather than a tassert to avoid creating fatal failures.

It's possible for failures to occur when re-parsing the key during output of $queryStats toDocument() due to fcv changes between when the key was created and when its trying to be read so reparsing of the shape errors. We can surface errors during $queryStats as a uassert as well and catch and throw specific error codes similar to the first creation of the key.