Boot method error about laradrop HOT 2 CLOSED

/**
 * The event handler mappings for the application.
 *
 * @var array
 */
protected $listen = [
    'Jasekz\Laradrop\Events\FileWasDeleted' => [
        'Jasekz\Laradrop\Handlers\Events\DeleteFile',
    ],
];

/**
 * Bootstrap the application services.
 *
 * @return void
 */
public function boot()
{
    parent::boot();
    
    if (! $this->app->routesAreCached()) {
        require __DIR__ . '/Http/routes.php';
    }
    
    $this->publishes([
        __DIR__ . '/config/config.php' => config_path('laradrop.php')
    ]);
    
    $this->publishes([
        __DIR__ . '/database/migrations/' => database_path('migrations')
    ], 'migrations');
    
    $this->publishes([
        __DIR__ . '/resources/assets' => public_path('vendor/jasekz/laradrop')
    ], 'public');
    
    $this->loadViewsFrom(__DIR__ . '/resources/views', 'laradrop');
    
    $this->loadTranslationsFrom(__DIR__ . '/resources/lang', 'laradrop');
}

/**
 * Register the application services.
 *
 * @return void
 */
public function register()
{        
}