Update post-code.js

Author: Oleksii Korshenko

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

@@ -34,7 +34,11 @@ define([
 
             option = options[value];
 
-            if (option && option['is_zipcode_optional']) {
+            if (!option) {
+                return;
+            }
+            
+            if (option['is_zipcode_optional']) {
                 this.error(false);
                 this.validation = _.omit(this.validation, 'required-entry');
             } else {