magento 2 stop checkout processing

I have this problem in magento 2 checkout.
I want that after a check in the billing address fields, if there is an error it stop checkout processing and not go to the success page.

How can I stop checkout processing in mixins?

file: set-billing-address-mixins.js

Here the code:

alert($t("Insert SDI field to have elettronic invoice!"));
$('div[name="shippingAddress.custom_attributes.sdi"] input').focus();
return false

return false doesn’t work.

Have you any other idea?