requestPrintTicket: switch to legacy, if no template list is configured

src/ATBAPP/ATBDeviceControllerPlugin.cpp

@@ -733,6 +733,15 @@ void ATBDeviceControllerPlugin::requestPrintTicket(nsDeviceControllerInterface::
 {
     QList<quint8> templateList = this->ticketTemplateList[ticketVariant];
 
+    if (templateList.isEmpty()) {
+        qCritical() << "ATBDeviceControllerPlugin::requestPrintTicket()";
+        qCritical() << "     TICKET_VARIANT: " << ticketVariant;
+        qCritical() << "     -> templateList is empty!";
+        qCritical() << "     -> switching to legacy interface";
+        this->requestPrintTicket(printingData);
+        return;
+    }
+
     // DEBUG
     qCritical() << "------------------------------------------------------------------------";
     qCritical() << "ATBDeviceControllerPlugin::requestPrintTicket()";