Admin Panel - after unsuccessful variant deletion, we should display error flash, not success one

Author: damianlegawiec

backend/app/controllers/spree/admin/variants_controller.rb

@@ -12,12 +12,12 @@ def destroy
         if @variant.destroy
           flash[:success] = Spree.t('notice_messages.variant_deleted')
         else
-          flash[:success] = Spree.t('notice_messages.variant_not_deleted')
+          flash[:error] = Spree.t('notice_messages.variant_not_deleted')
         end
 
         respond_with(@variant) do |format|
           format.html { redirect_to admin_product_variants_url(params[:product_id]) }
-          format.js  { render_js_for_destroy }
+          format.js { render_js_for_destroy }
         end
       end