Workers: Property 'onmessage' dos not exist

Im learning how to create worker threads but

deno-ts

deno-ts

says:

Property 'onmessage' does not exist on type 'Window & typeof globalThis'.

Property 'onmessage' does not exist on type 'Window & typeof globalThis'.

// worker.ts
self.onmessage = (message) => {
  // TODO: Do something with the message?
};

// worker.ts
self.onmessage = (message) => {
  // TODO: Do something with the message?
};

Am I missing some configuration?