adding sanity checking for incoming arguments

library/Zend/Filter/File/Rename.php

@@ -142,6 +142,11 @@ class Zend_Filter_File_Rename implements Zend_Filter_Interface
     public function getNewName($value, $source = false)
     {
         $file = $this->_getFileName($value);
+        
+        if (!is_array($file) || !array_key_exists('source', $file) || !array_key_exists('target', $file)) {
+            return $value;
+        }
+        
         if ($file['source'] == $file['target']) {
             return $value;
         }