Fatal error: Uncaught Error: Interface 'Vonage\Client\Credentials\Handler\HandlerInterface' not found in C:\xampp\htdocs\kit\vendor\vonage\client-core\src\Client\Credentials\Handler\AbstractHandler.php:9 Stack trace: #0 {main} thrown in C:\xampp\htdocs\kit\vendor\vonage\client-core\src\Client\Credentials\Handler\AbstractHandler.php on line 9