Following the instructions in the README results in the following error.

No event handlers were registered. This script does nothing.

Cloudflare accepts two formats for a worker. Service Worker where an event listener for fetch events must be registered or ES modules. This example worker needs to be expanded to include the event listener.

As an aside, the new support for useEsModules() in KotlinJS would be great but it doesn't yet create a module with a default export which Cloudflare requires.