Rocket - Early return from routes

Another Rocket example.

3 ways to handle error handling. I am not sure any of these would be a recommended way, but they are good for experimentation.

examples/rocket/early-return/Cargo.toml

[package]
name = "early-return"
version = "0.1.0"
edition = "2021"

# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html

[dependencies]
rocket = "0.5"
rocket_dyn_templates = { version = "0.1", features = ["tera"] }

examples/rocket/early-return/src/main.rs

#[macro_use]
extern crate rocket;

use rocket_dyn_templates::{context, Template};

#[get("/")]
fn index() -> Template {
    Template::render("index", context! {})
}

// deep
#[get("/deep/<number>")]
fn deep_indentation(number: &str) -> Template {
    match number.parse::<i32>() {
        Ok(number) => {
            // lots of processing with number
            Template::render("number", context! { number })
        }
        Err(err) => Template::render(
            "message",
            context! { message: format!("not a number {err}") },
        ),
    }
}

// early return using match
#[get("/early-match/<number>")]
fn early_with_match(number: &str) -> Template {
    let number = match number.parse::<i32>() {
        Ok(number) => number,
        Err(err) => {
            return Template::render(
                "message",
                context! { message: format!("not a number {err}") },
            )
        }
    };

    // lots of processing with number
    Template::render("number", context! { number })
}

#[get("/early-map/<number>")]
fn early_with_map_err(number: &str) -> Result<Template, Template> {
    let number = number.parse::<i32>().map_err(|err| {
        Template::render(
            "message",
            context! { message: format!("not a number {err}") },
        )
    })?;

    // lots of processing with number
    Ok(Template::render("number", context! { number }))
}

#[launch]
fn rocket() -> _ {
    rocket::build()
        .mount(
            "/",
            routes![
                index,
                deep_indentation,
                early_with_match,
                early_with_map_err
            ],
        )
        .attach(Template::fairing())
}

#[cfg(test)]
mod tests;

examples/rocket/early-return/src/tests.rs

use rocket::form::validate::Contains;
use rocket::http::Status;
use rocket::local::blocking::Client;

#[test]
fn main() {
    let client = Client::tracked(super::rocket()).unwrap();

    let response = client.get("/").dispatch();
    assert_eq!(response.status(), Status::Ok);
    assert_eq!(
        response.headers().get_one("Content-Type").unwrap(),
        "text/html; charset=utf-8"
    );
    assert!(response
        .into_string()
        .unwrap()
        .contains(r#"<a href="/deep/42">number</a> or <a href="/deep/hello">string</a>"#));

    for path in ["deep", "early-match", "early-map"] {
        let response = client.get(format!("/{path}/42")).dispatch();
        assert_eq!(response.status(), Status::Ok);
        assert_eq!(
            response.headers().get_one("Content-Type").unwrap(),
            "text/html; charset=utf-8"
        );
        assert_eq!(response.into_string(), Some("Number: 42".to_string()));

        let response = client.get(format!("/{path}/hello")).dispatch();
        assert_eq!(response.status(), Status::Ok);
        assert_eq!(
            response.headers().get_one("Content-Type").unwrap(),
            "text/html; charset=utf-8"
        );
        assert_eq!(
            response.into_string(),
            Some("Message: not a number invalid digit found in string".to_string())
        );
    }
}

examples/rocket/early-return/templates/index.html.tera

Try  
Deep: <a href="/deep/42">number</a> or <a href="/deep/hello">string</a><br>
Early return with match: <a href="/early-match/42">number</a> or <a href="/early-match/hello">string</a><br>
Early return map_err: <a href="/early-map/42">number</a> or <a href="/early-map/hello">string</a><br>

examples/rocket/early-return/templates/message.html.tera

Message: {{message}}

examples/rocket/early-return/templates/number.html.tera

Number: {{number}}