TypeError: 'NoneType' object is not iterable

[sentry-io[bot]]

Sentry Issue: GPODDERNET-GZ

TypeError: 'NoneType' object is not iterable
(13 additional frame(s) were not displayed)
...
  File "django/utils/decorators.py", line 43, in _wrapper
    return bound_method(*args, **kwargs)
  File "mygpo/decorators.py", line 113, in wrapper
    resp = f(*args, **kwargs)
  File "mygpo/api/__init__.py", line 34, in dispatch
    return super(APIView, self).dispatch(*args, **kwargs)
  File "django/views/generic/base.py", line 97, in dispatch
    return handler(request, *args, **kwargs)
  File "mygpo/api/subscriptions.py", line 51, in post
    rem = list(filter(None, actions.get('remove', [])))