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/admin/bulk_line_items_controller.rb

@@ -15,7 +15,10 @@ module Admin
 
       @line_items = @line_items.page(page).per(params[:per_page]) if pagination_required?
 
-      render json: { line_items: serialized_line_items, pagination: (pagination_required? ? pagination_data(@line_items) : nil) }
+      render json: {
+        line_items: serialized_line_items,
+        pagination: pagination_data(@line_items)
+      }
     end
 
     # PUT /admin/bulk_line_items/:id.json

app/controllers/api/exchange_products_controller.rb

@@ -86,7 +86,7 @@ module Api
 
       render json: {
         products: serialized_products,
-        pagination: pagination_required? ? pagination_data(paginated_products) : nil
+        pagination: pagination_data(paginated_products)
       }
     end
   end

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
 

app/controllers/concerns/pagination_data.rb

@@ -4,6 +4,8 @@ module PaginationData
   extend ActiveSupport::Concern
 
   def pagination_data(objects)
+    return unless objects.respond_to? :total_count
+
     {
       results: objects.total_count,
       pages: objects.total_pages,