Use German as default lang if no user is set

If the session is expired during the checkout, there was an fatal error.
Now the default language will be used.

copy_this/modules/suabo/lfnds/core/lfndsfacade.php

@@ -46,7 +46,7 @@ public function getFacade($sMode = '', $sForeignId = '') {
     $oViewConf = oxNew('oxviewconfig');
     $sModulePath = $oViewConf->getModulePath('suabolfnds');    
     $oUser = oxSession::getInstance()->getUser();
-    ($oUser->getLanguage() == 0 || $oUser->getLanguage() == -1) ? $sCountryCode = 'de' : $sCountryCode = 'en';  
+    (!$oUser || $oUser->getLanguage() == 0 || $oUser->getLanguage() == -1) ? $sCountryCode = 'de' : $sCountryCode = 'en';
     $sClientId = $myconfig->getConfigParam("sLfndsClientID");
     $sApiKey = $myconfig->getConfigParam("sLfndsApiKey");
     $sTheme = $myconfig->getConfigParam("sLfndsTheme");