In #28610 we've added exceptions to give better error messages in case one uses a form type that relies on symfony/intl. The problem is this can never happen, as sf/intl is a hard requirement per composer.json

This compared to the Validator component, where it's a soft requirement.

Is there any hassle-free approach for 4.x or 5.0 here? (in an effort to move it to require-dev instead).