impl `std::error::Error` for `cursive::theme::Error`

[septante]

Is there a reason that cursive::theme::Error doesn't implement the standard Error trait? I would like to write

fn load_theme(siv: &mut CursiveRunnable, path: PathBuf) -> anyhow::Result<()> {
    siv.load_theme_file(path)?;
    Ok(())
}

However, currently one has to write the following:

fn load_theme(siv: &mut CursiveRunnable, path: PathBuf) -> anyhow::Result<()> {
    match siv.load_theme_file(path) {
        Ok(_) => Ok(()),
        Err(e) => match e {
            cursive::theme::Error::Io(e) => Err(e.into()),
            cursive::theme::Error::Parse(e) => Err(e.into()),
        }
    }
}

I would be happy to open a PR for this if needed. Thank you!

[gyscos]

Hi! No reason, just didn't think about it. Would definitely appreciate a PR!