The LokiCheckout heavily depends upon another module Loki_Components. In this module, the barebones functionality of Loki Components: Alpine.js components that make AJAX calls to the backend. Other core modules like Loki_FieldComponents, Loki_MapComponents and LokiCheckout_Core are built on top of this.
When debugging is enabled, on various levels, detailed information comes available. For instance, in the browser Error Console, more debugging messages are displayed, allowing you to inspect issues on the JavaScript level. Whenever an exception occurs within the AJAX call, the exception message is appended to the AJAX output.