// <error-handler>
use actix_web::middleware::errhandlers::{ErrorHandlerResponse, ErrorHandlers};
use actix_web::{dev, http, web, App, HttpResponse, Result};

fn render_500<B>(mut res: dev::ServiceResponse<B>) -> Result<ErrorHandlerResponse<B>> {
    res.response_mut().headers_mut().insert(
        http::header::CONTENT_TYPE,
        http::HeaderValue::from_static("Error"),
    );
    Ok(ErrorHandlerResponse::Response(res))
}

fn main() {
    App::new()
        .wrap(
            ErrorHandlers::new()
                .handler(http::StatusCode::INTERNAL_SERVER_ERROR, render_500),
        )
        .service(
            web::resource("/test")
                .route(web::get().to(|| HttpResponse::Ok()))
                .route(web::head().to(|| HttpResponse::MethodNotAllowed())),
        );
}
// </error-handler>