revisit contract migration logic

[bekauz]

          Probably just a template, I also do it, but keep in mind that if you have those endpoints, and someone will try to migrate or you will try to do a reply, this will be successful, meaning you will be able to migrate successfully, and using the reply will be successful if you don't handle it.

Removing the endpoints will force a fail here and won't allow to to migrate or use reply by mistake, so ideally you would remove it (or comment it) to make sure it doesn't do what you don't want it to.

Originally posted by @Art3miX in #15 (comment)

following up on feedback on a pr above