Function spawn_logged 

fn spawn_logged<T: 'static>(
    what: &'static str,
    fut: impl Future<Output = Result<T>> + 'static,
) -> JoinHandle<Result<T>> 

Run the part of a call which must finish also if capnp-rpc drops the call, like once the client disconnects, in a task of its own, see task_result. Its error gets logged here as well, the client may be gone or have its reply already.