AttributeError: 'NoneType' object has no attribute 'next_window'

Clean install of HBL/6.0 from medkit, every two hours:

Mar 11 05:00:02 tudddis updater-supervisor: Traceback (most recent call last):
   File "/usr/bin/updater-supervisor", line 33, in <module>
    sys.exit(load_entry_point('svupdater==1.5.1', 'console_scripts', 'updater-supervisor')())
   File "/usr/lib/python3.9/site-packages/svupdater/__main__.py", line 87, in main
 AttributeError: 'NoneType' object has no attribute 'next_window'

100% related to the recent changes with update windows.

Automatic installation, the command that is actually run is '/usr/bin/updater-supervisor -d --autorun --rand-sleep --no-network-fail' + no auto_approve_start/end in UCI.

It's pretty clear that there should be a check for auto_approve_window() not returning None - auto_approve_window is optional...