Return a non-zero exit-code on error

[djipko]

First - thanks for an awesome CLI!!! Here's a small fix for an issue I ran into when gearing up for this year :)

This is a common (miss)-behavior of a lot of CLI utilities that rust
makes very easy to fix - by simply returning a Result type from the main()
function (which we already have). This will default to 1 for all
failures.

This is useful for scripting downloads and submissions, but is also
generally the right behavior of a unix utility on error.

We also remove logging the error as this is the default behavior when
returning result from main anyway.

Tested locally with

$ ./target/debug/aoc d --year 2021 --day 20 # not out yet when tested
Loaded session cookie from "~/.adventofcode.session".
Error: "Puzzle 20 of 2021 is still locked."
$ echo $?
1

[scarvalhojr]

That's great, thanks for that!

We could actually take a step further and drop the declaration of the result variable and let the match block return the results. Something like:

    let session_cookie = read_session_cookie(args.value_of("session"));

    match args.value_of("command").unwrap() {
        cmd if cmd == "download" || cmd == "d" => {
            let filename = args.value_of("file").unwrap();
            download_input(&session_cookie, year, day, filename)
        }
        cmd if cmd == "submit" || cmd == "s" => {
            let part = args.value_of("part").unwrap();
            let answer = args.value_of("answer").unwrap();
            submit_answer(&session_cookie, year, day, part, answer)
        }
        cmd if cmd == "read" || cmd == "r" => {
            read_puzzle(&session_cookie, year, day)
        }
        _ => unreachable!(),
    }
}

Wanna try and do that?

[djipko]

Sounds good - will re-spin later!

[scarvalhojr]

Looks great, thank you!