Laravel - ServiceProvider：给我错误500

Question

使用ServiceProvider后，Laravel给我一个错误500 ... 如果我删除：

我知道，不需要约束，因为没有DI，我正在经历......

GameController：

namespace App\Http\Controllers\Game;

use App;
use App\Http\Controllers\Controller;

class GameController extends Controller
{
    public function start(GameRepositoryInterface $gameRepository) {
        return $gameRepository->getLastAdd();
    }
}

GameServiceProvider：

namespace App\Providers\Game;

use Illuminate\Support\ServiceProvider;
use App\Http\Controllers\Game\StdGameRepository;
use App\Http\Controllers\Game\GameRepositoryInterface;

class GameServiceProvider extends ServiceProvider
{
    protected $defer = true;

    public function register() {
        dd('ici');
        $this->app->bind(StdGameRepository::class, function() {
           return new StdGameRepository();
        });

        $this->app->bind(GameRepositoryInterface::class, StdGameRepository::class);
    }

    public function provides() {
        return [GameRepositoryInterface::class];
    }
}

GameRepositoryInterface：

namespace App\Http\Controllers\Game;

interface GameRepositoryInterface
{
    public function getLastAdd();
}

StdGameRepository：

namespace App\Http\Controllers\Game;

class StdGameRepository implements GameRepositoryInterface
{
    private $lastAdd = "Testing";

    public function getLastAdd()
    {
        return $this->lastAdd;
    }
}