Description
The command to check URL throw an error and don't check URLs 

Steps to reproduce

1. Install clean eZ Platform v3.0
2. Log in to Admin and add the article with URL
3. Run bin/console ezplatform:check-urls

Actual:

Show error: Notice: Undefined property: eZ\Bundle\EzPublishCoreBundle\URLChecker\Handler\HTTPHandler::$configResolver  and links not verifing 

Expect:

Url check without display error