⏫ Forwardport of #13051 to 2.3-develop branch

Applied pull request patch https://github.com/magento/magento2/pull/13051.patch (created by @codekipple) based on commit(s):
  1. c8ff538

Author: magento-engcom-team

app/code/Magento/Ui/view/base/web/js/form/element/region.js

@@ -35,6 +35,11 @@ define([
                 return;
             }
             option = options[value];
+
+            if (typeof option === 'undefined') {
+                return;
+            }
+
             defaultPostCodeResolver.setUseDefaultPostCode(!option['is_zipcode_optional']);
 
             if (this.skipValidation) {