Steps to reproduce the issue

Joomla 4 beta 6
using config:set cli tool you can set invalid values in configuration.php

Expected result

Input validation

Actual result

php joomla.php config:set live_site="something that is not a url"

System information (as much as possible)

PHP 7.4.13 (cli) (built: Dec 23 2020 11:21:05) ( NTS )
Copyright (c) The PHP Group
Zend Engine v3.4.0, Copyright (c) Zend Technologies
    with Zend OPcache v7.4.13, Copyright (c), by Zend Technologies

Additional comments