닉네임 중복 확인 코드 추가, JWT 코드 추가

.gitmodules

@@ -0,0 +1,4 @@
+[submodule "config"]
+	path = config
+	url = https://github.com/Today-s-Gym/application.git
+	branch = "main"

src/main/java/com/todaysgym/todaysgym/config/exception/errorCode/MemberErrorCode.java

@@ -8,7 +8,8 @@
 @AllArgsConstructor
 public enum MemberErrorCode implements ErrorCode {
     EMPTY_MEMBER("MEMBER_001", "존재하지 않는 사용자입니다."),
-    NICKNAME_ERROR("MEMBER_002", "이미 존재하는 닉네임입니다.")
+    NICKNAME_ERROR("MEMBER_002", "이미 존재하는 닉네임입니다."),
+    ALREADY_EXIST("MEMBER_003", "이미 존재하는 사용자입니다.")
     ;
     private final String errorCode;
     private final String message;

src/main/java/com/todaysgym/todaysgym/member/MemberService.java

@@ -1,7 +1,7 @@
 package com.todaysgym.todaysgym.member;
 
-import com.todaysgym.todaysgym.exception.BaseResponse;
-import com.todaysgym.todaysgym.exception.BaseResponseStatus;
+import com.todaysgym.todaysgym.config.exception.BaseException;
+import com.todaysgym.todaysgym.config.exception.errorCode.MemberErrorCode;
 import lombok.RequiredArgsConstructor;
 import org.springframework.stereotype.Service;
 import org.springframework.transaction.annotation.Transactional;
@@ -19,13 +19,12 @@ public void join(Member member) {
         memberRepository.save(member);
     }
 
-    private BaseResponse<?> validateDuplicateMember(Member member) {
+    private void validateDuplicateMember(Member member) {
         Optional<Member> findMembers =
                 memberRepository.findByNickName(member.getNickName());
         if (!findMembers.isEmpty()) {
-            return new BaseResponse<>(BaseResponseStatus.Already_Exist);
+            throw new BaseException(MemberErrorCode.ALREADY_EXIST);
         }
-        else return new BaseResponse<>(BaseResponseStatus.SUCCESS);
     }
 
     public Member findOne(Long memberId) {