check address for required house number on WooCommerce checkout

functions.php

<?php
function wdt_address_field_validation() {

    $post_value = $_POST['billing_address_1'];

    if ( $post_value && ! preg_match( '/[0-9]+/', $post_value ) ) {

        throw new Exception( sprintf( __( 'Das Feld <strong>Straße</strong> muss eine <strong>Hausnummer</strong> beinhalten.', 'woocommerce' ) ) );
    }
}
add_action('woocommerce_checkout_process', 'wdt_address_field_validation', 10, 0);