Fatal error: Uncaught Error: Interface "Laravel\Socialite\Contracts\Provider" not found in C:\WebServer\htdocs\bookshelf\vendor\laravel\socialite\src\Two\AbstractProvider.php:13 Stack trace: #0 {main} thrown in C:\WebServer\htdocs\bookshelf\vendor\laravel\socialite\src\Two\AbstractProvider.php on line 13