Get Customer Details > Customer Object in api-docs.ecwid.com

`Ecwid.OnSetProfile.add(function(customer) {
  console.log(customer.email);
  console.log(customer.billingPerson.countryName);
});
`

Returns error cannot read properties of undefined (reading 'add')

Is there another way to get the customer who is visiting the site's information such as group id?