Error adding teams to StageGroup (aka Pool)

[goodtune]

When attempting to link teams to a pool in the admin interface, the following error is thrown:

10.244.9.99 - - [13/Apr/2024:03:18:23 +0000] "POST /admin/fixja/competition/1/seasons/53/division/230/stage/470/pool/122/ HTTP/1.1" 500 151 "https://www.internationaltouch.org/admin/fixja/competition/1/seasons/53/division/230/stage/470/pool/122/" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/17.4.1 Safari/605.1.15"
ERROR:django.request:Internal Server Error: /admin/fixja/competition/1/seasons/53/division/230/stage/470/pool/122/
Traceback (most recent call last):
  File "/workspace/.heroku/python/lib/python3.9/site-packages/touchtechnology/content/middleware.py", line 250, in middleware
    obj = Redirect.objects.get(source_url__exact=request.path)
  File "/workspace/.heroku/python/lib/python3.9/site-packages/django/db/models/manager.py", line 85, in manager_method
    return getattr(self.get_queryset(), name)(*args, **kwargs)
  File "/workspace/.heroku/python/lib/python3.9/site-packages/django/db/models/query.py", line 435, in get
    raise self.model.DoesNotExist(
touchtechnology.content.models.Redirect.DoesNotExist: Redirect matching query does not exist.

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/workspace/.heroku/python/lib/python3.9/site-packages/django/core/handlers/exception.py", line 47, in inner
    response = get_response(request)
  File "/workspace/.heroku/python/lib/python3.9/site-packages/django/core/handlers/base.py", line 181, in _get_response
    response = wrapped_callback(request, *callback_args, **callback_kwargs)
  File "/workspace/.heroku/python/lib/python3.9/site-packages/django/utils/decorators.py", line 43, in _wrapper
    return bound_method(*args, **kwargs)
  File "/workspace/.heroku/python/lib/python3.9/site-packages/tournamentcontrol/competition/decorators.py", line 184, in _decorated
    return f(request, *args, **kwargs)
  File "/workspace/.heroku/python/lib/python3.9/site-packages/django/utils/decorators.py", line 43, in _wrapper
    return bound_method(*args, **kwargs)
  File "/workspace/.heroku/python/lib/python3.9/site-packages/django/contrib/auth/decorators.py", line 21, in _wrapped_view
    return view_func(request, *args, **kwargs)
  File "/workspace/.heroku/python/lib/python3.9/site-packages/tournamentcontrol/competition/admin.py", line 1281, in edit_pool
    return self.generic_edit(
  File "/workspace/.heroku/python/lib/python3.9/site-packages/touchtechnology/common/sites.py", line 510, in generic_edit
    obj = form.save()
  File "/workspace/.heroku/python/lib/python3.9/site-packages/tournamentcontrol/competition/forms.py", line 616, in save
    self.instance.teams = self.cleaned_data.get("teams")
  File "/workspace/.heroku/python/lib/python3.9/site-packages/django/db/models/fields/related_descriptors.py", line 545, in __set__
    raise TypeError(
TypeError: Direct assignment to the reverse side of a related set is prohibited. Use teams.set() instead.