Socialite makes wrong redirect

I installed Laravel Socialite on Lumen 5.2, but can't make it work.

.ENV:

FB_KEY=xxx
FB_SECRET=xxx
FB_CALLBACK=http://lumen.app/auth/facebook/callback

config/services.php

<?php

return [
    'facebook' => [
        'client_id' => env('FB_KEY'),
        'client_secret' => env('FB_SECRET'),
        'redirect' => env('FB_CALLBACK'),
    ],
];

routes.php

$app->get('/auth/facebook',                       ['uses' => 'App\Http\Controllers\AuthController@redirectToProvider']);
$app->get('/auth/facebook/callback',              ['uses' => 'App\Http\Controllers\AuthController@handleProviderCallback']);

AuthController.php

public function redirectToProvider()
{
    Socialite::driver('facebook')->stateless()->redirect();
}

But when I open http://lumen.app/auth/facebook, it redirects me to FB page with an error The parameter app_id is required.

echo Socialite::driver('facebook')->stateless()->redirect()->getTargetUrl(); // https://www.facebook.com/v2.6/dialog/oauth?scope=email&response_type=code

This URL doesn't have client credentials, and I don't know why.

Does anybody have any ideas?