Create a new user in Auth0 managed db while migrating from custom db

Yes, the UX after having completed a migration could be improved; this is something that is already being tracked. I would need to check, but in theory, you can update the login script to just error out without making any external calls because if every users got migrated a call to this script indicates the user in question is not in Auth0 so it must not exist; hence just error out. For the get user script I think the noop would be to always return that the user does not exist because that script should also only be called after trying to find him among the migrated ones.