SendError

Convert the error back into the request that was originally sent.

Since the original request's body is consumed by sending it, the body in the returned request is empty. To add a new body to the request, use Request::with_body(), for example:

if let Err(e) = bereq.send("my_backend") {
    let new_body = Body::from("something new");
    let new_req = e.into_sent_req().with_body(new_body);
    new_req.send("my_other_backend")?;
}

Get the underlying cause of this SendError.

This is the same cause that would be returned by err.source().downcast_ref::<SendErrorCause>(), but more direct.