Attempt to assign property 'content' of non-object

<?php

namespace App\Http\Controllers;

use Illuminate\Http\Request;

class HomeController extends Controller {
    protected $layout = 'layouts.master';

    public function dashboard(){
        $this->layout->content = view('dashboard.index')->withTitle('Dashboard');

    }
}

mohon maaf saya adaptasi dari laravel 4.2 (tutorialnya), sambil liat dokumentasi kalau di laravel 4.2 gini dan kalau di 5.8 gini. saya memiliki notifikasi error  Attempt to assign property 'content' of non-object. ada yang bisa bantu?terimakasih