Merge pull request #199 from Team-MindWay/198-rec-deleted-500

추천 도서 삭제 500

src/main/java/com/mindway/server/v2/domain/rec/service/impl/DeleteRecServiceImpl.java

@@ -16,7 +16,7 @@
 public class DeleteRecServiceImpl implements DeleteRecService {
 
     private final RecRepository recRepository;
-    private UserUtil userUtil;
+    private final UserUtil userUtil;
 
     public void execute(Long id) {
         User user = userUtil.getCurrentUser();