Description:
------------
Trying to fetch DB result into a SimpleXMLElement instance produces an incorrect error message.

Reproduce code:
---------------
$q = new PDO('sqlite::memory:');
$q->exec ("CREATE TABLE test (a)");
$q->exec ("INSERT INTO test (a) VALUES (1)");
var_dump ($q->query ("SELECT a FROM test")->fetchAll(PDO::FETCH_CLASS, 'SimpleXMLElement', array ('<root/>')));


Expected result:
----------------
Some consistent error message.

Actual result:
--------------

Warning:  PDOStatement::fetchAll() [function.fetchAll]: Node no longer exists in c:\program files\apache group\Apache\htdocs\standart\index.php on line 6

array(1) {
  [0]=>
  object(SimpleXMLElement)#3 (0) {
  }
}