TypeError: 'AnonymousUser' object is not iterable

[sentry]

Sentry Issue: CONFERENCE-SITES-5T

TypeError: 'AnonymousUser' object is not iterable
  File "django/utils/functional.py", line 247, in inner
    return func(self._wrapped, *args)
  File "django/db/models/sql/query.py", line 1149, in check_related_objects
    for v in value:
  File "django/db/models/sql/query.py", line 1320, in build_filter
    self.check_related_objects(join_info.final_field, value, join_info.opts)
  File "django/db/models/sql/query.py", line 1415, in _add_q
    split_subq=split_subq, check_filterable=check_filterable,
  File "django/db/models/sql/query.py", line 1393, in add_q
    clause, _ = self._add_q(q_object, self.used_aliases)
...
(32 additional frame(s) were not displayed)

[martey]

This error is caused by non-logged-in users accessing the reviewing section. We need to make sure that all reviewing pages redirect to a login page.