Can't parse input object

[DAThosting]

Hi there,

I know the project is a few years old but I get the following error in PHP 8:
AH01071: Got error 'PHP message: PHP Fatal error: Uncaught org\\nameapi\\client\\fault\\ServiceException: Unexpected late exception translation, caused by: Can't parse input object

My code looks like:

require_once( __DIR__ . '/vendor/optimaize/nameapi-client-php/src/org/nameapi/client/services/ServiceFactory.php');

use org\nameapi\ontology\input\context\Context;
use org\nameapi\ontology\input\context\Priority;
use org\nameapi\client\services\ServiceFactory;
use org\nameapi\ontology\input\entities\person\NaturalInputPerson;
use org\nameapi\ontology\input\entities\person\name\InputPersonName;

$context = Context::builder()
	->place('US')
	->priority(Priority::REALTIME())
    ->build();

$serviceFactory = new ServiceFactory('9f138864435cXXXXXXXXXXXXXXXXXXXX-user1', $context);

$personNameParser = $serviceFactory->parserServices()->personNameParser();
$inputPerson = NaturalInputPerson::builder()
    ->name(InputPersonName::westernBuilder()
        ->fullname( "John Doe" )
        ->build())
    ->build();
$parseResult = $personNameParser->parse($inputPerson);
var_dump($parseResult);

What am I doing wrong?