Lock SignUp with Custom Database always shows "We're sorry, something went wrong when attempting to sign up."

Hello,

I’m implementing custom database scripts “Create” and “Get User”. I can see the that the script “Create” is not executed when “Get User” returns a user. However, Lock shows error “We’re sorry, something went wrong when attempting to sign up.” when user is found. I expect to see an error “A user with such email already exists”

My “Get User” is very simple:

function get_user(email, callback) {
    return callback(null, {"email": "john@gmail.com"});
}

I was following the docs from here: https://auth0.com/docs/connections/database/custom-db/templates/get-user

Best,
Mikhail