update the destroy api

@@ -58,7 +58,8 @@ class ItemViewSet(viewsets.ViewSet):
     def destroy(self, request, pk):
         if request.method == 'DELETE':
             print(pk)
-            item = Item.objects.get(item_id = pk)
+            item = get_object_or_None(Item, item_id=pk)
+            if item != None:
                 if item.is_folder == True: # 폴더는 삭제 안되도록 처리
                     return Response({'message': 'This item is folder.'}, status=status.HTTP_200_OK)
                 item.is_deleted = True