I have recently been running into trouble uploading photos on my website, and I’ve found this error literally printed in my logs, rather than being logged as an error. It’s all happening in the guts of flask, and not my code, so I’m a bit stumped. Any guidance on where I should be looking to fix things would be helpful:

Traceback (most recent call last):   File "/layers/google.python.pip/pip/lib/python3.11/site-packages/flask/app.py", line 1473, in wsgi_app
    response = self.full_dispatch_request()
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/layers/google.python.pip/pip/lib/python3.11/site-packages/flask/app.py", line 882, in full_dispatch_request
    rv = self.handle_user_exception(e)
         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/layers/google.python.pip/pip/lib/python3.11/site-packages/flask/app.py", line 880, in full_dispatch_request
    rv = self.dispatch_request()
         ^^^^^^^^^^^^^^^^^^^^^^^
  File "/layers/google.python.pip/pip/lib/python3.11/site-packages/flask/app.py", line 865, in dispatch_request
    return self.ensure_sync(self.view_functions[rule.endpoint])(**view_args)  # type: ignore[no-any-return]
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/srv/app/views.py", line 605, in view_media_file
    return app.mongo.send_file(filename)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/layers/google.python.pip/pip/lib/python3.11/site-packages/flask_pymongo/__init__.py", line 206, in send_file
    response.set_etag(fileobj.md5)
  File "/layers/google.python.pip/pip/lib/python3.11/site-packages/werkzeug/sansio/response.py", line 498, in set_etag
    self.headers["ETag"] = quote_etag(etag, weak)
                           ^^^^^^^^^^^^^^^^^^^^^^
  File "/layers/google.python.pip/pip/lib/python3.11/site-packages/werkzeug/http.py", line 888, in quote_etag
    if '"' in etag:
       ^^^^^^^^^^^
TypeError: argument of type 'NoneType' is not iterable