update

app/service/lesson.js

@@ -645,7 +645,7 @@ class LessonService extends CrudService {
       if (c) cla = c.name;
       for (const l of list) {
         const { subname, date } = l;
-        res.push({ subname, date, term, class: cla });
+        if (cla && subname && date && term) { res.push({ subname, date, term, class: cla }); }
       }
     }
     res = _.uniqWith(res, _.isEqual);