When an event has duration zero because the start and end times are identical, ZeroDivisionError's are raised repeatedly for the corresponding
Traceback (most recent call last): File "/home/fortysixandtwo/install/lib/python3.9/site-packages/confy/widgets.py", line 130, in _on_draw prc = min(max(pos/dur, 0.0), 1.0) ZeroDivisionError: float division by zero
Arguably a zero duration event does not make a lot of sense (or I'm simply lacking imagination). LibrePlanet 21 has a number of such events on sunday (16:55 - 16:55).
A patch should reach you any minute now :)