In some cases, in '__construct', the head section of a Document/Html is not defined. So a fatal error appends.

Class : Zend_Search_Lucene_Document_Html / Line : 106
(@version    $Id: Html.php 16971 2009-07-22 18:05:45Z mikaelkael $)

...

// Remove additional HEAD section
$xpath = new DOMXPath($this->_doc);
$head  = $xpath->query('/html/head')->item(0);
$head->parentNode->removeChild($head);                   <-- FATAL ERROR

A test should be done on '$head' to see if it's correctly defined before removing child.

Bye