Laravel 5 - 多个自定义服务提供商

I've created a service provider called \App\Providers\HelperServiceProvider.php with this content:

<?php namespace App\Providers;

use Illuminate\Support\ServiceProvider;
use Session;
use View;

class HelperServiceProvider extends ServiceProvider {

    /**
     * Bootstrap the application services.
     *
     * @return void
     */
    public function boot()
    {
    }

    /**
     * Register the application services.
     *
     * @return void
     */
    public function register()
    {
        foreach (glob(app_path().'/Helpers/*.php') as $filename){
            require_once($filename);
        }
    }

}

And also included in providers in \config\app.php

This works fine until recently I wanted to add a new provider for different purposes. So I created a new one App\Providers\ComposerServiceProvider.php

<?php namespace App\Providers;

use Illuminate\Support\ServiceProvider;
use Session;
use View;

class ComposerServiceProvider extends ServiceProvider {

    /**
     * Bootstrap the application services.
     *
     * @return void
     */
    public function boot()
    {
        # This content doesn't really matter. It still doesn't work even if I remove it.
        # View composer for partials.alert
        # Some code
    }

    /**
     * Register the application services.
     *
     * @return void
     */
    public function register()
    {
    }

}

And included in the config too so it looks like this:

<?php   
        /* ^Some other things
         *
         * Application Service Providers...
         */
        'App\Providers\AppServiceProvider',
        'App\Providers\BusServiceProvider',
        'App\Providers\ConfigServiceProvider',
        'App\Providers\EventServiceProvider',
        'App\Providers\RouteServiceProvider',
        'App\Providers\HelperServiceProvider',
        'App\Providers\ComposerServiceProvider',

But it came out as Internal Server Error. It works fine when I take out from the providers config. I've tried everything I can think of. I tried removing everything inside boot(), changing the order of the providers, renaming the providers, but none of them worked. I can't get to the php/apache log file for other technical reason. Is there any problem with this implementation that I missed?