error_handling.rs

#[derive(Debug)]
pub enum Err {
    JSONError(serde_json::Error),
    HTTPError(reqwest::Error),
}

macro_rules! convert_error {
    ($a:ty, $b:ident, $c:expr) => {
        impl From<$a> for $b {
            fn from(err: $a) -> Self {
                $c(err)
            }
        }
    }
}

convert_error!(serde_json::Error, Err, Err::JSONError);
convert_error!(reqwest::Error, Err, Err::HTTPError);