DOMPDF Error (vendor\dompdf\dompdf\src\Helpers.php:840) and (dompdf\dompdf\src\Helpers.php:503)

So this is my controller

<?php

namespace App\Http\Controllers;

use App\Model\Catatan_Mahasiswa;
use App\User;
use Illuminate\Http\Request;
use Barryvdh\DomPDF\Facade as PDF;

class LaporanController extends Controller
{
    public function jurnal_mahasiswa(User $mahasiswa)
    {
        $jurnal = Catatan_Mahasiswa::where('id_mahasiswa', $mahasiswa->id_mahasiswa)->latest()->get();

        $pdf = PDF::loadView('laporan.jurnal-mahasiswa', compact('jurnal', 'mahasiswa'));
        return $pdf->download('jurnal-mahasiswa');
    }
}