Catch traceback from presumably incorrect committee.import

A presumably incorrect committee import should not throw a traceback.
Unfortunately I only have the traceback and not the import file.

INFO:openslides_backend.shared.handlers.base_handler:Performing action committee.import.
[ERROR] Error handling request POST /system/action/handle_request
Traceback (most recent call last):
  File "/usr/local/lib/python3.12/site-packages/gunicorn/workers/gthread.py", line 479, in handle
    keepalive = self.handle_request(req, conn)
                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/gunicorn/workers/gthread.py", line 678, in handle_request
    respiter = self.wsgi(environ, resp.start_response)
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/app/openslides_backend/http/application.py", line 164, in __call__
    return self.wsgi_application(environ, start_response)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/app/openslides_backend/http/application.py", line 154, in wsgi_application
    response = self.dispatch_request(request)
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/app/openslides_backend/http/application.py", line 103, in dispatch_request
    response_body, access_token = view_instance.dispatch(request)
                                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/app/openslides_backend/http/views/base_view.py", line 121, in dispatch
    return func(request)
           ^^^^^^^^^^^^^
  File "/app/openslides_backend/http/views/action_view.py", line 52, in action_route
    response = handle_action_in_worker_thread(
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/app/openslides_backend/action/action_worker.py", line 94, in handle_action_in_worker_thread
    raise action_worker_thread.exception
  File "/app/openslides_backend/action/action_worker.py", line 265, in run
    self.response = self.handler.handle_request(
                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/app/openslides_backend/action/action_handler.py", line 140, in handle_request
    results = self.execute_write_requests(
              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/app/openslides_backend/action/action_handler.py", line 229, in execute_write_requests
    write_requests, data = get_write_requests(*args)
                           ^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/app/openslides_backend/action/action_handler.py", line 279, in parse_actions
    write_request, results = self.perform_action(
                             ^^^^^^^^^^^^^^^^^^^^
  File "/app/openslides_backend/action/action_handler.py", line 328, in perform_action
    write_request, results = action.perform(
                             ^^^^^^^^^^^^^^^
  File "/app/openslides_backend/action/action.py", line 187, in perform
    instance = self.base_update_instance(instance)
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/app/openslides_backend/action/mixins/import_mixins.py", line 232, in base_update_instance
    return super().base_update_instance(instance)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/app/openslides_backend/action/action.py", line 340, in base_update_instance
    return self.update_instance(instance)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/app/openslides_backend/action/actions/committee/import_.py", line 52, in update_instance
    self.create_models(rows)
  File "/app/openslides_backend/action/actions/committee/import_.py", line 169, in create_models
    self.execute_other_action(CommitteeUpdateAction, update_committee_data)
  File "/app/openslides_backend/action/action.py", line 734, in execute_other_action
    write_request, action_results = action.perform(
                                    ^^^^^^^^^^^^^^^
  File "/app/openslides_backend/action/action.py", line 176, in perform
    self.instances = list(self.get_updated_instances(action_data))
                          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/app/openslides_backend/action/actions/committee/update.py", line 82, in get_updated_instances
    for id_ in [
               ^
TypeError: Value after * must be an iterable, not NoneType