fix : ajax 오류 메시지 추출로직변경

as-is
	let message = JSON.parse(JSON.parse(request.responseText).resBody.message);
	alert(message.errorMsg);

to-be
    let message = JSON.parse(request.responseText).resBody.result;
    alert(message);

src/main/webapp/WEB-INF/views/mngr/promtn/coupon/CouponPkRegistC.jsp

@@ -1145,9 +1145,9 @@ since : 2024.01.04 추지훈 최초 생성
                         }
                     }
                 }/*, error : function(request, status, error) {
-                    let message = JSON.parse(JSON.parse(request.responseText).resBody.message);
+                    let message = JSON.parse(request.responseText).resBody.result;
 
-                    alert(message.errorMsg);
+                    alert(message);
                 }*/
             });
         }