Dev: Coveralls Uncaught Error: Class "Config\Autoload" not found

[kenjis]

PHP Fatal error: Uncaught Error: Class "Config\Autoload" not found in /home/runner/work/CodeIgniter4/CodeIgniter4/system/Test/Mock/MockAutoload.php:16

See #7924 (comment)

Ref sebastianbergmann/phpcov#101

[kenjis]

It seems phpcov does not use the custom autoloader at all.
Then Config classes are impossible to be loaded.

But if that is the case, why didn't we get the error before?