How do I prevent missing house numbers with Address Ninja?

Open Address Ninja from Apps in your Shopify admin. On the home page, click Require house numbers. In the Countries card, choose All countries, Only these countries, or Except these countries. Add countries with the Search countries field. Under Address, choose Shipping address, Billing address, or Shipping and billing addresses. Click Turn on. If you changed a setting, the button reads Save and turn on. Customers must enter a number and at least two letters in the first address line. To change the error message, open the Error message card.