Add check if IBAN is set before adding the QR part

htdocs/core/modules/facture/doc/pdf_swissqr.modules.php

@@ -855,9 +855,12 @@ class pdf_swissqr extends ModelePDFFactures
                 }
 
                 // Add page for the Swiss QR-invoice
+                if (isset($object->iban))
+                {
                     $pdf->AddPage();
                     $this->_pagehead($pdf, $object, 0, $outputlangs);
                     $this->qrinvoice($pdf, $object, $outputlangs, $conf);
+                }
 
                 $pdf->Close();