老师确认增加群组

mec-biz/src/main/java/com/ym/mec/biz/service/impl/StudentRegistrationServiceImpl.java

@@ -169,7 +169,8 @@ public class StudentRegistrationServiceImpl extends BaseServiceImpl<Long, Studen
         studentRegistrationDao.insert(studentRegistration);
         //增加报名学生数
         MusicGroupSubjectPlan musicOneSubjectClassPlan = musicGroupSubjectPlanService.getMusicOneSubjectClassPlan(studentRegistration.getMusicGroupId(), studentRegistration.getSubjectId());
-        musicOneSubjectClassPlan.setApplyStudentNum(musicOneSubjectClassPlan.getApplyStudentNum() + 1);
+        int applyNum = musicOneSubjectClassPlan.getApplyStudentNum() == null ? 0 : musicOneSubjectClassPlan.getApplyStudentNum();
+        musicOneSubjectClassPlan.setApplyStudentNum(applyNum + 1);
         return studentRegistration;
     }