'Filters' Bug

[dayrui]

1、application/Config/Constants.php:
define('APP_NAMESPACE', 'MyApp');
2、application/Config/Router.php:
$routes->setDefaultNamespace('MyApp\Controllers');
3、application/Controller/Home.php:
`<?php namespace MyApp\Controllers;

class Home extends \CodeIgniter\Controller
{
public function index()
{
return view('welcome_message');
}
}
`

go http://localhost/public/index.php

Error:

ErrorException #1
Uncaught Error: Class 'App\Filters\DebugToolbar' not found i