Add guard clause and remove conditionals

Sometimes the objects are not paginated. In this case we need to avoid trying to render pagination data, as it will throw an error. This guard clause also means we can remove messy conditionals from several controllers.

app/controllers/api/orders_controller.rb

@@ -16,7 +16,7 @@ module Api
 
       render json: {
         orders: serialized_orders(orders),
-        pagination: pagination_required? ? pagination_data(orders) : nil
+        pagination: pagination_data(orders)
       }
     end