implement streaming response body

[CrowdHailer]

I use this in a lustre application.
The relevant code looks like

effect.from(fn(dispatch) {
  promise.await(fetch.send_bits(request), fn(response) {
    dispatch(StartStreaming)
    let assert Ok(response) = response
    use result <- promise.await(fetch.stream_bytes_body(response.body, fn(bytes) {
      dispatch(StreamedBody(bytes))
      promise.resolve(Nil)
    }))
    dispatch(StreamResult(result))
    promise.resolve(Nil)
  })
  Nil
})

It seems to be working ok for me.

[CrowdHailer]

because there's only one error kind maybe this should just be an Error(Nil) that is returned?