TypeError lors de déconnection

On peut la trigger à partir de https://git.eleves.ens.fr/dlesbre/48h-des-jeux/-/tree/bug en se connectant via un compte clipper (le mien était superuser mais je doute que ça influe) puis en se déconnectant (via le lien du site).

On obtient le traceback suivant:

Internal Server Error: /authens/logout
Traceback (most recent call last):
  File "/home/dorian/Programs/kde/48h-des-jeux/venv/lib/python3.9/site-packages/django/core/handlers/exception.py", line 47, in inner
    response = get_response(request)
  File "/home/dorian/Programs/kde/48h-des-jeux/venv/lib/python3.9/site-packages/django/core/handlers/base.py", line 181, in _get_response
    response = wrapped_callback(request, *callback_args, **callback_kwargs)
  File "/home/dorian/Programs/kde/48h-des-jeux/venv/lib/python3.9/site-packages/django/views/generic/base.py", line 70, in view
    return self.dispatch(request, *args, **kwargs)
  File "/home/dorian/Programs/kde/48h-des-jeux/venv/lib/python3.9/site-packages/django/utils/decorators.py", line 43, in _wrapper
    return bound_method(*args, **kwargs)
  File "/home/dorian/Programs/kde/48h-des-jeux/venv/lib/python3.9/site-packages/django/views/decorators/cache.py", line 44, in _wrapped_view_func
    response = view_func(request, *args, **kwargs)
  File "/home/dorian/Programs/kde/48h-des-jeux/venv/lib/python3.9/site-packages/django/contrib/auth/views.py", line 119, in dispatch
    next_page = self.get_next_page()
  File "/home/dorian/Programs/kde/48h-des-jeux/venv/lib/python3.9/site-packages/authens/views.py", line 150, in get_next_page
    next_page = urlunparse(
  File "/usr/lib/python3.9/urllib/parse.py", line 501, in urlunparse
    return _coerce_result(urlunsplit((scheme, netloc, url, query, fragment)))
  File "/usr/lib/python3.9/urllib/parse.py", line 513, in urlunsplit
    url = '//' + (netloc or '') + url
TypeError: can only concatenate str (not "NoneType") to str
[20/Sep/2021 12:53:14] "GET /authens/logout HTTP/1.1" 500 99672