PHP error in woo order overview

The Query Monitor shows the following php error in the wc order overview

Hinweis	

Undefined index: dhl_tracking_url_language	

20	

wp-content/plugins/dhl-for-woocommerce/includes/class-pr-dhl-wc-order-paket.php:520
PR_DHL_WC_Order_Paket->get_tracking_url()
wp-content/plugins/dhl-for-woocommerce/includes/abstract-pr-dhl-wc-order.php:377
PR_DHL_WC_Order->get_tracking_link()
wp-content/plugins/dhl-for-woocommerce/includes/class-pr-dhl-wc-order-paket.php:865
PR_DHL_WC_Order_Paket->get_tracking_link()
wp-content/plugins/dhl-for-woocommerce/includes/class-pr-dhl-wc-order-paket.php:898
PR_DHL_WC_Order_Paket->add_order_label_column_content()
wp-includes/class-wp-hook.php:309
do_action('manage_shop_order_posts_custom_column')
wp-admin/includes/class-wp-posts-list-table.php:1349
WP_Posts_List_Table->column_default()
wp-admin/includes/class-wp-list-table.php:1450
WP_List_Table->single_row_columns()
wp-admin/includes/class-wp-posts-list-table.php:1383
WP_Posts_List_Table->single_row()
wp-admin/includes/class-wp-posts-list-table.php:795
WP_Posts_List_Table->_display_rows()
wp-admin/includes/class-wp-posts-list-table.php:772
WP_Posts_List_Table->display_rows()
wp-admin/includes/class-wp-list-table.php:1362
WP_List_Table->display_rows_or_placeholder()
wp-admin/includes/class-wp-list-table.php:1289
WP_List_Table->display()
wp-admin/edit.php:477