ICS with multiple "STATUS" fields aren't handled correctly

Some Calendar tools, create ICS objects of invitations with multiple Status fields. This seems for me to happen on Kopano, when I change a reccurring invitation Item to not be recurring anymore for one day. (A.e. recurring daily meeting is rescheduled to a later point in the day).

This looks like this:

~ grep STATUS .calendars/Calendar/040000008200E00074xxxxxx9743BD251B5C9FBD.ics
STATUS:CONFIRMED
STATUS:CONFIRMED
STATUS:CONFIRMED

When I then want to use khal to see the events or khal interactive, following happens:

Traceback:

Traceback (most recent call last):
  File "/usr/bin/khal", line 5, in <module>
    main_khal()
  File "/usr/lib/python3.9/site-packages/click/core.py", line 829, in __call__
    return self.main(*args, **kwargs)
  File "/usr/lib/python3.9/site-packages/click/core.py", line 782, in main
    rv = self.invoke(ctx)
  File "/usr/lib/python3.9/site-packages/click/core.py", line 1259, in invoke
    return _process_result(sub_ctx.command.invoke(sub_ctx))
  File "/usr/lib/python3.9/site-packages/click/core.py", line 1066, in invoke
    return ctx.invoke(self.callback, **ctx.params)
  File "/usr/lib/python3.9/site-packages/click/core.py", line 610, in invoke
    return callback(*args, **kwargs)
  File "/usr/lib/python3.9/site-packages/click/decorators.py", line 21, in new_func
    return f(get_current_context(), *args, **kwargs)
  File "/usr/lib/python3.9/site-packages/khal/cli.py", line 624, in at
    rows = controllers.khal_list(
  File "/usr/lib/python3.9/site-packages/khal/controllers.py", line 262, in khal_list
    current_events = get_events_between(
  File "/usr/lib/python3.9/site-packages/khal/controllers.py", line 198, in get_events_between
    event_string = event.format(agenda_format, relative_to=(start, end), env=env)
  File "/usr/lib/python3.9/site-packages/khal/khalendar/event.py", line 623, in format
    attributes['status'] = self.status + ' ' if self.status else ''
TypeError: can only concatenate list (not "str") to list

Debugging

Tried to debugg the issue. Looks like event.py can't handle a list of "STATUS". Tried adding a print on line 662 of event.py to print out the state:

Normal invitationICS:

~ khal at 2021-01-12 09:00


CONFIRMED
CONFIRMED
CONFIRMED
2021-01-12 09:00
09:00-10:30 meeting for this and taht

Invitation which isn't recurring for one day:

~ khal at 2021-01-11 13:00
[vText('b'CONFIRMED''), vText('b'CONFIRMED'')]
[vText('b'CONFIRMED''), vText('b'CONFIRMED'')]
[vText('b'CONFIRMED''), vText('b'CONFIRMED'')]
2021-01-11 13:00
13:00-15:00 Training  ⟳

Quickfix

My quickfix for now was to add following lines inside event.py on line 661

    @property
    def status(self):
        status=self._vevents[self.ref].get('STATUS', '')
        if type(status) == list:
            return status[0]
        else:
          return status

This just returns only the first item of a status if it's a list. But I guess it could be done better by writing a sanitize function somewhere else.

Start in event.py around the status property and reproduce the failure with an ICS file containing multiple STATUS fields. Determine how repeated STATUS values should be represented, then verify that khal can display the event without the reported TypeError.