You are not allowed to delete "None" on the restriction types settings page

When you go to the Restriction types tab of the settings (admin/store/settings/restrictshipping/types) and click the add a restriction link you get this message:
You are not allowed to delete "None" .

This is because of the code at line 473:

<?php
  if ($type_id==0) {
    drupal_set_message(t('You are not allowed to delete "None" .'), 'error');
    drupal_goto('admin/store/settings/restrictshipping/types');
  }
?>

Because the $type_id is NULL