Error when try to sending email in Laravel

I was try to make some email to send email acticvation code when someone register. so i make it an event called UserRegistered. On the UserRegistered i pass the user data like this:

public $user;

/**
 * Create a new event instance.
 *
 * @return void
 */
public function __construct(User $user)
{
    $this->user = $user;
}

and here's my listener:

public function handle(UserRegistered $event)
    {
        Mail::to($event->user)->send(new SendActivationCode($event));
    }

and here the SendActivatiionCode class:

protected $user;
    /**
     * Create a new message instance.
     *
     * @return void
     */
    public function __construct(User $user)
    {
        $this->user = $user;
    }

    /**
     * Build the message.
     *
     * @return $this
     */
    public function build()
    {
        return $this->markdown('mails.user.activation')->with([
            'name' => $this->user->name,
            'token' => $this->user->token,
        ]);
    }

but i got this errors:

"Type error: Argument 1 passed to Illuminate\Mail\PendingMail::send() must be an instance of Illuminate\Mail\Mailable, instance of App\Listeners\SendActivationCode given, called in E:\laragon\www\blog\app\Listeners\SendActivationCode.php on line 30 ◀"

so what can make me get this errors and how to fix it? thanks.

via Chebli Mohamed