és a stack trace, ami kicsit jobban leírja a hibát:
2020-07-17T12:54:07+00:00 CRITICAL Uncaught Exception: Invalid product. in /wp-content/plugins/woocommerce/includes/data-stores/class-wc-product-data-store-cpt.php:165
Stack trace:
#0 /wp-content/plugins/woocommerce/includes/class-wc-data-store.php(159): WC_Product_Data_Store_CPT->read(Object(WC_Product))
#1 /wp-content/plugins/woocommerce/includes/abstracts/abstract-wc-product.php(135): WC_Data_Store->read(Object(WC_Product))
#2 /wp-content/plugins/billingo/class.billingo.php(326): WC_Product->__construct(11665)
#3 /wp-content/plugins/billingo/class.billingo.php(60): WC_Billingo::generateInvoice(12081)
#4 /wp-includes/class-wp-hook.php(287): WC_Billingo::ajax_generateInvoice('')
#5 /wp-includes/class-wp-hook.php(311): WP_Hook->apply_filters('', Array)
#6 /wp-content/plugins/woocommerce/includes/data-stores/class-wc-product-data-store-cpt.php file in line 165
