When creating a built-in fields definition billing_address and error can occur when the the field is *not* marked as *read-only* - as it's expected to be read-only for the developers (on the Account details form - the user can still update the billing address through the Credit Card Details form).

However, no error is visible to the admin user, the "New field definition" form is just reloaded, no field is highlighted with an error, and no toast alert is shown.

I think, the page should at least show a toast alert, so the user is aware of what went wrong.

Ideally, additionally, the read-only checkbox should be already checked and not modiable for this field.