[Vuejs]-Pusher receive event with null values

I think you write the constructor of your event class wrong.
Here you put extra $ before message and user variable

    public function __construct($message, User $user)
    {
        $this->$message = $message;
        $this->$user = $user;
    }

It should be like following one.

    public function __construct($message, User $user)
    {
        $this->message = $message;
        $this->user = $user;
    }