'<' not supported between instances of 'NoneType' and 'int'

This seems to happen when Liquid Ozone levels are not fetched yet (new structure or ESI failure)

Traceback (most recent call last):
  File "/home/allianceserver/venv/auth/lib/python3.8/site-packages/celery/app/trace.py", line 451, in trace_task
    R = retval = fun(*args, **kwargs)
  File "/home/allianceserver/venv/auth/lib/python3.8/site-packages/celery/app/trace.py", line 734, in __protected_call__
    return self.run(*args, **kwargs)
  File "/home/allianceserver/venv/auth/lib/python3.8/site-packages/structures/tasks.py", line 139, in send_jump_fuel_notifications_for_config
    JumpFuelAlertConfig.objects.get(pk=config_pk).send_new_notifications()
  File "/home/allianceserver/venv/auth/lib/python3.8/site-packages/structures/models/notifications.py", line 1212, in send_new_notifications
    if jump_gate.jump_fuel_quantity() < self.threshold:
TypeError: '<' not supported between instances of 'NoneType' and 'int'

https://gitlab.com/ErikKalkoken/aa-structures/-/blob/master/structures/models/notifications.py#L1212

Maybe a quick check if jump_gate.jump_fuel_quantity() is not None might help here.