feat：空指针保护

domain/service/group_s/group_op.go

@@ -182,9 +182,11 @@ func (s *GroupService) GroupIn(userId uint64, externalId string, groupUuid strin
 				if err != nil {
 					model.Log.Errorf("GroupIn GetGroupUserOrInit err:%v, groupId:%v, userId:%v", err, groupUuid, userId)
 				}
+				if groupUser != nil {
 					if err := groupUser.SetRoomInTime().Persistent(); err != nil {
 						model.Log.Errorf("GroupIn groupUser Persistent err:%v, groupId:%v, userId:%v", err, groupUuid, userId)
 					}
+				}
 
 				// 发送进群TIM信令。fixme: 应该发在event处理
 				isVip, err := user.CheckVip()