Worker needed for robot.txt value

Here’s my Robots worker:

async function handleRequest(request) {
  const init = {
    headers: {
      'content-type': 'text/plain;charset=UTF-8',
    },
  }
  return new Response(someHTML, init)
}
addEventListener('fetch', event => {
  return event.respondWith(handleRequest(event.request))
})
const someHTML = `User-agent: *
Disallow: /
`