Rust: simple and quiet Error result — when eprintln is enough. No painful error handling.

example_error_result.rs

// SPDX-License-Identifier: MIT
use std::fmt; 
use clap::Parser; //just for argument parsing
use colored::Colorize; //colored output

#[derive(Debug)]
pub struct QuietErr(Option<String>);
impl fmt::Display for QuietErr {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        if let Some(ref msg) = self.0 {
            write!(f, "{}", msg)
        } else {
        write!(f, "")
        }
    }   
}
impl std::error::Error for QuietErr {}

// Clap args
#[derive(Parser, Debug)]
#[command(author, version, about, long_about = None)]
struct Args {
    #[arg(short, long, value_name = "NAME")]
    name: Option<String>,
}

fn main() -> Result<(), Box<dyn std::error::Error>> {
    let args = Args::parse();
    
    if let Some(name) = args.name {
        name_test(&name)?;
    } else {
        let err = format!("No name provided!");
        eprintln!("{} {}", "Error:".red(), err);
        return Err(Box::new(QuietErr(Some(err)))); //with return for e.g. GUI programs
    }
}

fn name_test(name: &str) -> Result<(), Box<dyn std::error::Error>> {
  if !name.is_empty() {
        eprintln!("Heyo {}! {}", name.bold(), "It Works!".red());
        return Err(Box::new(QuietErr(None))); //Quiet
    }
  Ok(());
}