Fix component check

backend/src/appointment/controller/calendar.py

@@ -402,15 +402,21 @@ def list_events(self, start, end):
                 continue
 
             vevent = e.vobject_instance.vevent
+            if not vevent:
+                continue
+
+            event_components = vevent.components()
 
             # Ignore events with missing datetime data
-            if not vevent or not vevent.dtstart or (not vevent.dtend and not vevent.duration):
+            if 'dtstart' not in event_components or (
+                'dtend' not in event_components and 'duration' not in event_components
+            ):
                 continue
 
             # Mark tentative events
             tentative = status == 'tentative'
 
-            title = vevent.summary.value if vevent.summary else l10n('event-summary-default')
+            title = vevent.summary.value if 'summary' in event_components else l10n('event-summary-default')
             start = vevent.dtstart.value
             # get_duration grabs either end or duration into a timedelta
             end = start + e.get_duration()