容错处理

src/views/teacher/create_course/step_four/NewTask.vue

@@ -387,7 +387,7 @@ function addTaskToCSItem() {
         ({ courseware_id, group_id_selected_info }) => {
           return {
             courseware_id,
-            group_id_selected_info: group_id_selected_info.length <= 0 ? '[]' : group_id_selected_info
+            group_id_selected_info: group_id_selected_info?.length <= 0 ? '[]' : group_id_selected_info
           };
         }
       );