use std::io;
use errortools::FormatError;
#[derive(Debug, thiserror::Error)]
enum AppError {
#[error("failed to load config")]
Config(#[source] io::Error),
}
fn main() {
let err = AppError::Config(io::Error::new(io::ErrorKind::NotFound, "missing.toml"));
println!("one line: {}", err.one_line());
println!();
println!("tree:\n{}", err.tree());
let dyn_err: &dyn core::error::Error = &err;
println!();
println!("dyn: {}", dyn_err.one_line());
}