An issue with the database query that's supposed to retrieve the "notification" object.

[c0d33py]

The AttributeError occurs when attempting to call "_base_manager" on the model class associated with the "notification" object. This suggests that the "notification" object is expected to be a Django model instance, but it is None, hence the error.

Internal Server Error: /notifications/api/all_list/
Traceback (most recent call last):
  File "/project/env/lib/python3.10/site-packages/django/core/handlers/exception.py", line 55, in inner
    response = get_response(request)
  File "/project/env/lib/python3.10/site-packages/django/core/handlers/base.py", line 197, in _get_response
    response = wrapped_callback(request, *callback_args, **callback_kwargs)
  File "/project/env/lib/python3.10/site-packages/django/views/decorators/cache.py", line 62, in _wrapped_view_func
    response = view_func(request, *args, **kwargs)
  File "/project/env/lib/python3.10/site-packages/notifications/views.py", line 191, in live_all_notification_list
    all_list = get_notification_list(request)
  File "/project/env/lib/python3.10/site-packages/notifications/helpers.py", line 25, in get_notification_list
    if notification.target:
  File "/project/env/lib/python3.10/site-packages/django/contrib/contenttypes/fields.py", line 250, in __get__
    rel_obj = ct.get_object_for_this_type(pk=pk_val)
  File "/project/env/lib/python3.10/site-packages/django/contrib/contenttypes/models.py", line 179, in get_object_for_this_type
    return self.model_class()._base_manager.using(self._state.db).get(**kwargs)
AttributeError: 'NoneType' object has no attribute '_base_manager'

[AlvaroLQueiroz]

Can you give the steps to reproduce this error?