Fix a bug when no Zend_Log is registered with Zend_Registry as 'log'.

library/Unl/XsrfToken.php

@@ -75,7 +75,7 @@ class Unl_XsrfToken
      */
     public function verify($tokenId, $onceOnly = TRUE)
     {
-        if (Zend_Registry::get('log') instanceof Zend_Log) {
+        if (Zend_Registry::isRegistered('log') && Zend_Registry::get('log') instanceof Zend_Log) {
             $log = Zend_Registry::get('log');
         } else {
             $log = new Zend_Log();