lfb_event_end_feedback_async: assertion 'LFB_IS_EVENT (self)' failed
This kind of assertion failure appears sometimes:
apr 21 06:44:52 pureos gnome-clocks[1240]: lfb_event_end_feedback_async: assertion 'LFB_IS_EVENT (self)' failed
Happens on a Librem 5 running PureOS with gnome-clocks version 40.0.