Rust Custom Error Type

use std::fmt;

#[derive(Debug)]
pub enum AppError {
    NotFound(String),
    Unauthorized,
    Database(String),
    Validation(Vec<String>),
}

impl fmt::Display for AppError {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        match self {
            AppError::NotFound(msg) => write!(f, "Not found: {msg}"),
            AppError::Unauthorized => write!(f, "Unauthorized"),
            AppError::Database(msg) => write!(f, "Database error: {msg}"),
            AppError::Validation(errs) => write!(f, "Validation: {}", errs.join(", ")),
        }
    }
}

impl std::error::Error for AppError {}