Elm Json Decode - do nothing, get original string back

I'm using the-sett/elm-aws-core to get information from the AWS API, which unfortunately is very very inconsistent. Most of the endpoints return JSON and that works fine with that lib, which takes a JSON Decoder to make a request, but the EC2 endpoint returns XML (because why not).

The lib doesn't have any options not to decode JSON as far as I can tell, which does not work at all :

let ec2 region = Service.defineRegional "ec2""2016-11-15" Service.QUERY Service.SignV4 (Service.setXmlNamespace "https://ec2.amazonaws.com/doc/2016-11-15/") region in
let params = [("Action", "DescribeImages"), ("Version", "2016-11-15"), ("Owner.1", "self")] in
Http.request "DescribeImages" GET "/" Http.emptyBody JSONDECODERHERE |> Http.addQuery params |> Http.send (ec2 region) creds |> Task.attempt msg

Failed : Problem with the given value:

"<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n<DescribeImagesResponse .......

As you can see in there you need to pass a JSON Decoder to Http.request, but that, of course, fails when receiving XML. Is there a way to build a "fake" JSON decoder that would actually do nothing and just pass on the raw string? I tried using Decode. string but that's still actually decoding it, which fails. If there is a way I could then run an XML decoder manually on it in my update function, which would be fine.

Thank you