api: fix datetimes for multiple agendas when no subscriptions & overlaps (#76217)

chrono/api/views.py

@@ -934,6 +934,7 @@ class MultipleAgendasDatetimes(APIView):
         check_overlaps = bool(payload.get('check_overlaps'))
 
         entries = Event.objects.none()
+        if agendas:
             for agenda in agendas:
                 if show_past_events:
                     entries |= agenda.get_past_events(

tests/api/datetimes/test_events_multiple_agendas.py

@@ -1695,3 +1695,10 @@ def test_datetimes_multiple_agendas_overlapping_events(app):
 
     resp = app.get('/api/agendas/datetimes/', params={'agendas': 'foo-bar,foo-bar-2'})
     assert ['overlaps' not in x for x in resp.json['data']]
+
+    # no subscription found for this user
+    resp = app.get(
+        '/api/agendas/datetimes/',
+        params={'subscribed': 'all', 'user_external_id': 'xxx', 'check_overlaps': True},
+    )
+    assert len(resp.json['data']) == 0