I like the way Axum for Rust handles this. All response handlers return something that implements IntoResponse. Lots of types implement IntoResponse, thus making the simple cases really streamlined.

async fn create_user( Json(payload): Json<CreateUser>, ) -> impl IntoResponse {

    let user = User {
        id: 1337,
        username: payload.username,
    };

    // this will be converted into a JSON response
    // with a status code of `201 Created`
    (StatusCode::CREATED, Json(user))

}

If the handler is complex enough that branches can't all return the same type, you can just add .into_response() to each return site, and now you're just returning a response, which also implements IntoResponse (as a no-op).

This avoids the problem discussed in this article while also avoiding much of the boilerplate of manually building responses.