Laravel file manager illegal offset type

I'm trying to install the Laravel file manager to my Laravel 5.0 app. It installs without problem with composer.

I add service providers to config/app.php

Unisharp\Laravelfilemanager\LaravelFilemanagerServiceProvider::class,
Intervention\Image\ImageServiceProvider::class,

but when I Publish the package's config and assets :

php artisan vendor:publish --tag=lfm_config
php artisan vendor:publish --tag=lfm_public

am getting an error.

  Illegal offset type

I can't seem to find where the mistake is. Thanks guys.

via Chebli Mohamed