Automatic plan update fails because of missing version object

  File "/srv/aleksis/envs/production/lib/python3.9/site-packages/aleksis/apps/chronos/models.py", line 1302, in automatic_plan_signal_receiver
    automatic_plan.check_update(sender)
  File "/srv/aleksis/envs/production/lib/python3.9/site-packages/aleksis/apps/chronos/models.py", line 1270, in check_update
    date_start = date_end = version.object.date
AttributeError: 'NoneType' object has no attribute 'date'