Merge improve testing

core/serializers/feedback.py

@@ -155,7 +155,7 @@ class FeedbackSerializer(DynamicFieldsModelSerializer):
             try:
                 score = data.get('score')
                 submission = data.get('of_submission')
-            except KeyError as err:
+            except KeyError:
                 raise serializers.ValidationError(
                     'You need a score and a submission.')