Merge branch '323-graphqlerror-nonetype-object-has-no-attribute-id' into 'master'

Resolve "GraphQLError: 'NoneType' object has no attribute 'id'"

Closes #323

See merge request !432

aleksis/apps/alsijil/schema/participation_status.py

@@ -119,9 +119,9 @@ class ExtendParticipationStatusToAbsenceBatchMutation(graphene.Mutation):
             return participation, absence
 
         else:
-            # No base absence, simply create one
+            # No base absence, simply create one if absence reason is given
             data = dict(
-                reason_id=participation.absence_reason.id,
+                reason_id=participation.absence_reason.id if participation.absence_reason else None,
                 person=participation.person,
             )