Sporadic failure in read_span_flatbuffer tests

[lokitoth]

BadNamespace_FeatureValuesHashMismatch will occasionally cause an SEH exception (unclear where because the system does not have the source file at time the string is generated).

I have not had the ability to reproduce it locally; it only seems to happen on Windows on artifacts produced with build systems configured using the VS Generator in CI, and only in the GitHub Actions CI