Fix: bug on UBL notice not hiding (#618)

includes/settings/class-wcpdf-settings-ubl.php

@@ -146,7 +146,7 @@ public function save_order_taxes( $order ) {
 	public function vat_coc_required_for_ubl_invoice() {
 		$invoice_ubl_settings = WPO_WCPDF()->settings->get_document_settings( 'invoice', 'ubl' );
 
-		if ( isset( $invoice_ubl_settings['enabled'] ) && ( ! isset( $this->general_settings['vat_number'] ) || ! isset( $this->general_settings['coc_number'] ) ) ) {
+		if ( isset( $invoice_ubl_settings['enabled'] ) && ( ! isset( WPO_WCPDF()->settings->general_settings['vat_number'] ) || ! isset( WPO_WCPDF()->settings->general_settings['coc_number'] ) ) ) {
 			$message = sprintf(
 				/* translators: 1. General Settings, 2. UBL Settings  */
 				__( 'You\'ve enabled UBL output for a document, but some essential details are missing. Please ensure you\'ve added your VAT and CoC numbers in the %1$s. Also, specify your tax rates in the %2$s.', 'woocommerce-pdf-invoices-packing-slips' ),