I cannot confirm that this resolves our error, because it occurs only sporadically in our tests and I was not able to enforce it egain.
But I can confirm that this patch does not break anything.

Regarding the code: In line 100 False gets returned instead of a string.
For consistency reasons I would prefer returning None and checking for is not None.
However, both versions will work :)

Thank you for checking. In order to keep the patch minimal I will keep it as-is since it will work.