fix menu attributes error

app/views/origami/addorders/_menu_item.json.jbuilder

@@ -31,15 +31,13 @@ json.is_sub_item  item.is_sub_item
 json.unit         item.unit
 
 # Item Sets of Menu Item
-json.item_sets item.item_sets.includes(:menu_item_instances) do |its|
+json.item_sets item.item_sets do |its|
   json.id                 its.id
   json.name               its.name
   json.alt_name           its.alt_name
   json.min_selectable_qty its.min_selectable_qty
   json.max_selectable_qty its.max_selectable_qty
-  json.instances its.menu_item_instances do |i|
-    json.id  i.id
-  end
+  json.instances          its.menu_item_instances.map { |i| {id: i.id} }
 end
 
 json.attributes attr_format