...
async fn delete_question(
    id: String,
    store: Store
) -> Result<impl warp::Reply, warp::Rejection> {
    match store.questions.write().await.remove(&QuestionId(id)) {
        Some(_) => {
            return Ok(
                warp::reply::with_status(
                    "Question deleted",
                    StatusCode::OK
                )
            )
        },
        None => return Err(warp::reject::custom(Error::QuestionNotFound)),
    }
}
...