Fatal error: Uncaught Error: Class "League\OAuth2\Client\Provider\AbstractProvider" not found in /opt/lampp/htdocs/forum/flarum/vendor/league/oauth2-facebook/src/Provider/Facebook.php:14 Stack trace: #0 {main} thrown in /opt/lampp/htdocs/forum/flarum/vendor/league/oauth2-facebook/src/Provider/Facebook.php on line 14