In eZOOConverter::handleInlineNode() there's a call to itself, but missing one parameter:
$return = self::handleInlineNode( $inlineNode );
should be:
$return = self::handleInlineNode( $inlineNode, $generator );

Also, in eZOOGenerator::handleElement() there's a faulty xml string
$contentXML .= "<text text:style-name='Defualt'></text>" . "\n";
should be:
$contentXML .= "<text text:style-name='Default'></text>" . "\n";