Index: class-wp-error.php
===================================================================
--- class-wp-error.php  (revision 29520)
+++ class-wp-error.php  (working copy)
@@ -75,7 +75,7 @@
         * @return mixed Property.
         */
        public function __get( $name ) {
-               return $this->$name;
+               return ( isset( $this->$name ) ? $this->$name : null );
        }

        /**