https://github.com/ncsa/vacation_calendar_sync/issues/new

[PhongT16]

The events parameter in the filter function can be empty (IndividualCalendar.py Line: 179)
Add:
if events: return None

In OutlookCalendar.py line 63:
tmp = IndividualCalendar.process_individual_calendars(individual_calendars, current_date, end_date)
if tmp: individual_calendars_events.extend(tmp)

Note:
You can use Assignment Expressions to make it one line:
if tmp := IndividualCalendar.process_individual_calendars(individual_calendars, current_date, end_date): individual_calendars_events.extend(tmp)