localhost send an invalid response code igniter 4 - php

Question

I'm just learning CI4 from Youtube "web programming unpas" on episode 9 insert data (its using indonesia language). Well I followed the course and tried to insert data. After insert data to database, it will be redirected to the index file.
So the error is showing localhost send an invalid response
Idk what's the problem
Here is the code
routes.php
$routes->get('/', 'pages::index');
$routes->get('/komik/create', 'komik::create');
$routes->get('/komik/(:segment)', 'komik::detail/$1');
controller/komik.php
<?php
namespace App\Controllers;
use App\Models\komikmodel;
class komik extends BaseController
{
protected $komikmodel;
public function __construct()
{
$this->komikmodel = new komikmodel();
}
public function index()
{
$data = [
'title' => 'Daftar Komik' ,
'komik' => $this->komikmodel->getkomik()
];
return view('komik/index', $data);
}
public function detail($slug)
{
$data = [
'title' => 'Detail Komik',
'komik' => $this->komikmodel->getkomik($slug)
];
if(empty($data['komik']))
{
throw new \CodeIgniter\Exceptions\PageNotFoundException('Judul Komik '. $slug. 'Tidak Ditemukan');
}
return view('komik/detail', $data);
}
public function create()
{
$data = [
'title' => 'Form Tambah Data Komik'
];
return view('/komik/create', $data);
}
public function save()
{
$slug = url_title($this->request->getVar('judul'), '-', true);
$this->komikmodel->save([
'judul' => $this->request->getVar('judul'),
'slug' => $slug,
'penulis' => $this->request->getVar('penulis'),
'penerbit' => $this->request->getVar('penerbit'),
'sampul' => $this->request->getVar('sampul')
]);
session()->setFlashData('pesan', 'Data berhasil di tambahkan!');
return redirect()->to('/komik');
}
}
Any advice will be appreciated