导入行政课表时如果年级无教师提示

slive/src/main/java/com/xhkjedu/slive/service/xz/XzService.java

             List<XzClassVo> classlst = classMapper.listClassByXzid(schoolid, gradeid);
             String classids = classlst.stream().map((XzClassVo::getClassid)).map(String::valueOf).collect(Collectors.joining(","));
             List<CTeacherVo> teachers = classTeacherMapper.listTeacherByClassIds(classids);//获取班级教师
+            if(N_Utils.isListEmpty(teachers)) return new ResultVo(1,"请设置班级任教老师");
             String teacherids = teachers.stream().map((CTeacherVo::getTeacherid)).map(String::valueOf).collect(Collectors.joining(","));
             List<CTeacherVo> subjects = classTeacherMapper.listSubjectByTeacherIds(teacherids);//获取教师科目
             String subjectids = subjects.stream().map(CTeacherVo::getSubjectid).distinct().collect(Collectors.joining("','"));