actix_web_web_error

#[macro_use]
extern crate actix_web;
use failure::Fail;

use actix_web::{
    http, middleware, web, App, HttpResponse,
    HttpServer, error
};
use serde::{Deserialize, Serialize};
use std::env;

#[derive(Fail, Debug)]
enum WebError {
    #[fail(display = "Invalid id '{}'", id)]
    InvalidIdError { id: i32 },
    #[fail(display = "Invalid request, please try again later")]
    RandomInternalError,
}

impl error::ResponseError for WebError {
    fn error_response(&self) -> HttpResponse {
        match *self {
            WebError::InvalidIdError{..} => HttpResponse::new(http::StatusCode::BAD_REQUEST),
            WebError::RandomInternalError => HttpResponse::new(http::StatusCode::INTERNAL_SERVER_ERROR) 
        }
    }
}


#[derive(Debug, Clone, Serialize, Deserialize)]
struct Bookmark {
    id: i32,
    url: String,
}

#[get("by-id/{id}")]
async fn bookmarks_by_id(id: web::Path<(i32)>) -> Result<HttpResponse, WebError> {
    if *id < 10 {
        Ok(HttpResponse::Ok().json(Bookmark{
            id: *id,
            url: "https://blog.x5dd.xyz".into(),
        }))
    }
    else {
        Err(WebError::InvalidIdError { id: *id })
    }
}

#[actix_rt::main]
async fn main() -> std::io::Result<()> {
    env::set_var("RUST_LOG", "actix_web=debug");
    env_logger::init();

    HttpServer::new(|| {
        App::new()
            .wrap(middleware::Logger::default())
            .service(
                web::scope("/bookmarks")
                    .service(bookmarks_by_id)
            )
            .route("/underconstruction", 
                 web::get().to(|| async Result::<HttpResponse, WebError>::Err(WebError::RandomInternalError)),
            )
    })
    .bind("127.0.0.1:8081")?
    .run()
    .await
}

I am following a book on Rust and the source is available here:
https://github.com/PacktPublishing/Rust-Programming-Cookbook/tree/master/Chapter08/web-errors

I have noticed that the actin_web is outdated and I am trying to update the code with actin_web 2. However, I just can't get the example to compile

dependencies

actix-web = "2"
env_logger = "0.6"
actix-files = "0"
actix-rt = "1"
serde = { version = "1.0", features = ["derive"] }
failure = "0"

I am getting an error on line 62. I have also added the async keyword still no luck

web::get().to(|| async Result::<HttpResponse, WebError>::Err(WebError::RandomInternalError)),