[Refact] #5 커스텀익셉션 super로 원인출력

Author: Shinjongyun

src/main/java/com/WhoIsRoom/WhoIs_Server/global/common/exception/BusinessException.java

@@ -7,7 +7,8 @@
 public class BusinessException extends RuntimeException {
     private final ErrorCode errorCode;
 
-    public BusinessException(ErrorCode errorCode) {
-        this.errorCode = errorCode;
+    public BusinessException(ErrorCode code) {
+        super(code.getMessage());
+        this.errorCode = code;
     }
-}
+}