\Drupal::config('system.date')->get('country.default') now has validation and can now be null

Quick glance on how it's used: https://git.drupalcode.org/search?search=country.default&nav_source=navb...

Is this issue about Drupal core? I don't see relation between system.date/country.default and currency module.

I linked where it gets used in currency in comment #2.

There was a change that allows this to be NULL, this module has a test and a fallback so likely can be closed since if country.default is NULL then currency will just use: $this::DEFAULT_LOCALE