Add default amend object to lesson details

aleksis/apps/chronos/frontend/components/calendar_feeds/details/LessonDetails.vue

@@ -163,6 +163,13 @@ export default {
             value: "comment",
           },
         ],
+        default: {
+          subject: "",
+          teachers: [],
+          rooms: [],
+          cancelled: false,
+          comment: ""
+        },
       },
     };
   },