Pager Error Invalid file: Pagers(slash)bs_full.php

Maybe CodeIgniter exception feedback for these cases could be written somehow less cryptic or with a more explicit complain

It is true.
But how do we improve it?

CI shows:

Invalid file: Pagers\bs_full.php

This shows bs_full.php in the namespace Pagers is invalid.

Any idea?

ci-phpunit-test | CodeIgniter Testing Guide | CodeIgniter 3 to 4 Upgrade Helper