No need for thiserror as well as anyhow.

src/error-handling/error-contexts.md

@@ -7,14 +7,7 @@ custom error types:
 ```rust,editable,compile_fail
 use std::{fs, io};
 use std::io::Read;
-use thiserror::Error;
-use anyhow::{Context, Result};
-
-#[derive(Error, Debug)]
-enum ReadUsernameError {
-    #[error("Found no username in {0}")]
-    EmptyUsername(String),
-}
+use anyhow::{Context, Result, bail};
 
 fn read_username(path: &str) -> Result<String> {
     let mut username = String::with_capacity(100);
@@ -23,7 +16,7 @@ fn read_username(path: &str) -> Result<String> {
         .read_to_string(&mut username)
         .context("Failed to read")?;
     if username.is_empty() {
-        return Err(ReadUsernameError::EmptyUsername(String::from(path)).into());
+        bail!("Found no username in {path}");
     }
     Ok(username)
 }
@@ -39,7 +32,8 @@ fn main() {
 
 <details>
 
-* `anyhow::Result<T>` is generic and it can hold any `Error` implementation without changing the type signature.
+* `anyhow::Result<V>` is a type alias for `Result<V, anyhow::Error>`.
+* `anyhow::Error` is generic and it can hold any `Error` implementation without changing the type signature.
 * Actual error type inside of it can be extracted for examination if necessary.
 * Functionality provided by `anyhow::Result<T>` may be familiar to Go developers, as it provides similar usage patterns and ergonomics
   of `(T, error)` from Go.