校验优化

im-admin/ruoyi-im/src/main/java/org/dromara/im/service/impl/ImAgentServiceImpl.java

@@ -299,8 +299,8 @@ public class ImAgentServiceImpl implements IImAgentService {
             LambdaQueryWrapper<ImUser> exist = new LambdaQueryWrapper<>();
             exist.eq(ImUser::getUniqueToken, token);
             exist.eq(ImUser::getId, customerId);
-            ImUser existUser = userMapper.selectOne(exist);
-            if(ObjectUtil.isEmpty(existUser)){
+            boolean existUser = userMapper.exists(exist);
+            if(!existUser){
                 throw new RuntimeException("异常数据");
             }
             wrapper.set(ImAgent::getDefaultKefuId, customerId);