Debugging Refactor Snippets

// Before
let r = &data.items[0];
data.items.push(item);
use_ref(r);
 
// After
let snapshot = data.items[0].clone();
data.items.push(item);
use_val(snapshot);

// Before
let cache = Rc<RefCell<Cache>>::new(...);
tokio::spawn(async move { cache.borrow_mut().fill().await });
 
// After
let cache = Arc::new(tokio::sync::Mutex::new(Cache::new()));
let c = cache.clone();
tokio::spawn(async move { c.lock().await.fill().await });

// Before
async fn get(Path(id): Path<u64>) -> Json<User> {
    Json(db.fetch(id).await.unwrap())
}
 
// After
async fn get(Path(id): Path<u64>) -> Result<Json<User>, ApiError> {
    let user = db.fetch(id).await?.ok_or(ApiError::NotFound)?;
    Ok(Json(user))
}

// Before
std::fs::read_to_string(path)?
 
// After
tokio::task::spawn_blocking(move || std::fs::read_to_string(path)).await??

// Before
let x = user_input as u8;
 
// After
let x = u8::try_from(user_input).map_err(|_| Error::OutOfRange)?;