学校升级优化

sapi/src/main/java/com/xhkjedu/sapi/service/system/SchoolService.java

     private void checkUpTime() throws Exception {
         //获取区域限制学年升级时间
         TCloud cloud = cloudMapper.getCloudUpTime();
+        if (N_Utils.isEmpty(cloud.getStarttime())) throw new Exception("未设置升级时间，请联系区管理员");
+
         if (!ApiUtil.compareCurrDateTime(cloud.getStarttime(), cloud.getStoptime())) {
             throw new Exception("不在学年升级时间范围，禁止升级");
         }