مشكل با افزونه request a quote

[MARZI1 0]

سلام هنگامي كه دكمه تبديل quote to order رو ميزنم با خطاي زير مواجه ميشم 

Fatal error: Uncaught Error: Call to undefined method WP_Error::add_product() in C:xampphtdocswordpresswp-contentpluginswoocommerce-request-a-quoteadminmeta-boxesquotesconvert-quote-to-order.php:39 Stack trace: #0 C:xampphtdocswordpresswp-contentpluginswoocommerce-request-a-quoteadminclass-af-r-f-q-admin.php(171): include_once() #1 C:xampphtdocswordpresswp-includesclass-wp-hook.php(294): AF_R_F_Q_Admin->afrfq_update_quote_details(802) #2 C:xampphtdocswordpresswp-includesclass-wp-hook.php(316): WP_Hook->apply_filters('', Array) #3 C:xampphtdocswordpresswp-includesplugin.php(484): WP_Hook->do_action(Array) #4 C:xampphtdocswordpresswp-includespost.php(4373): do_action('save_post_addif...', 802, Object(WP_Post), true) #5 C:xampphtdocswordpresswp-includespost.php(4486): wp_insert_post(Array, false, true) #6 C:xampphtdocswordpresswp-adminincludespost.php(419): wp_update_post(Array) #7 C:xampphtdocswordpresswp-adminpost.php(227): edit_post() #8 {main} thrown in C:xampphtdocswordpresswp-contentpluginswoocommerce-request-a-quoteadminmeta-boxesquotesconvert-quote-to-order.php on line 39