move_dates_for_testing throws misleading errors

Occuring when called on the Untis test data, which does not have to be moved:

Traceback (most recent call last):
  File "/usr/local/bin/aleksis-admin", line 8, in <module>
    sys.exit(aleksis_cmd())
  File "/usr/local/lib/python3.9/dist-packages/aleksis/core/__main__.py", line 14, in aleksis_cmd
    execute_from_command_line(sys.argv)
  File "/usr/local/lib/python3.9/dist-packages/django/core/management/__init__.py", line 419, in execute_from_command_line
    utility.execute()
  File "/usr/local/lib/python3.9/dist-packages/django/core/management/__init__.py", line 413, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/usr/local/lib/python3.9/dist-packages/django/core/management/base.py", line 354, in run_from_argv
    self.execute(*args, **cmd_options)
  File "/usr/local/lib/python3.9/dist-packages/django/core/management/base.py", line 398, in execute
    output = self.handle(*args, **options)
  File "/usr/local/lib/python3.9/dist-packages/aleksis/apps/untis/management/commands/move_dates_for_testing.py", line 93, in handle
    raise RuntimeError("You need at least one validity range to move data.")
RuntimeError: You need at least one validity range to move data.