Fatal error: Uncaught TypeError: Argument 1 passed to DOMXPath::__construct() must be an instance of DOMDocument, instance of stdClass given in /jats-conversion-master/tests/index.php:129 Stack trace: #0 /jats-conversion-master/tests/index.php(129): DOMXPath->__construct() #1 /jats-conversion-master/tests/index.php(24): SS_JATS_HTML->convert() #2 {main} thrown in /jats-conversion-master/tests/index.php on line 129