Cancelled Occurrence replaced by a new Event/Occurrence causes occurrences_after to fail

[dwasyl]

Where there is an Event with a cancelled Occurrence, but another Event has been scheduled in place of the original at the same time, it causes EventListManager.occurrences_after() to fail at next_occurrence = heapq.heappop(occurrences)[0] with an '<' not supported between instances of 'generator' and 'generator' error.

Part of the issue seems to be that EventListManager.occurrences_after() doesn't employ the same logic as Event.get_occurrences() to work persisted occurrences into the generator set.

For example, in a case where an Event has only a single Occurrence and that Occurrence is cancelled, how should that be treated here? In either case, it causes occurrences_after() to fail which isn't the correct behaviour.

The use of OccurrenceReplacer happens at the end, but it has already failed due to match Occurrences being added to the heap.