[fix] UserController checkNickName 수정

Author: Hyeromon

src/main/java/org/dfbf/soundlink/domain/user/controller/UserController.java

@@ -29,10 +29,7 @@ public class UserController {
     @GetMapping("/checkNickName")
     @Operation(summary = "닉네임 중복 확인", description = "닉네임이 이미 사용중인지 확인.")
     public ResponseResult checkNickName(@RequestParam String nickName){
-        boolean exists = userService.checkNickName(nickName);
-        return exists
-                ? new ResponseResult(ErrorCode.DUPLICATE_NICKNAME) //중복 닉네임
-                : new ResponseResult(ErrorCode.NOT_DUPLICATE_NICKNAME);
+        return userService.checkNickName(nickName);
     }
 
     @GetMapping

src/main/java/org/dfbf/soundlink/domain/user/service/UserService.java

@@ -168,8 +168,12 @@ public ResponseResult checkEmail(String email){
     }
 
     //닉네임 중복 확인
-    public boolean checkNickName(String nickName){
-        return userRepository.existsByNickName(nickName);
+    public ResponseResult checkNickName(String nickName){
+        boolean exists =userRepository.existsByNickName(nickName);
+        if(exists){
+            return new ResponseResult(ErrorCode.DUPLICATE_NICKNAME);
+        }
+        return new ResponseResult(ErrorCode.NOT_DUPLICATE_NICKNAME);
     }
 
     //refreshToken을 쿠키로 설정