When I post a new resource, I have an error 500: ``` ldp_1 | super().perform_create(serializer, **kwargs) ldp_1 | File "/app/djangoldp/views.py", line 122, in perform_create ldp_1 | if hasattr(self.model._meta, 'auto_author') and isinstance(self.request.user, settings.AUTH_USER_MODEL): ldp_1 | TypeError: isinstance() arg 2 must be a type or tuple of types ``` URL: ``` POST: http://127.0.0.1:8000/threads/33/message_set/ ``` Payload: ```json [{"@id":"./","http://happy-dev.fr/owl/#text":"Message test\n"}] ``` I use the last version of djangoldp in sib-app-data-server. I don't know if it's related to django or to the new version of sib-core.