It is now possible to choose that patient code is required when creating a new patient.
This is done under SYSTEM - SETTINGS - GLOBAL - REQUIRED FIELDS

If there is a need of creating a patient without a code, then you can now choose the option "None" in the system.

If you set the code to "0" to indicate there is no code on this patient, then the systems gives a pop-up message if there are other patients marked with "0".