You can also use let else.

let (Some(count\_str), Some(item)) = (it.next(), it.next()) else {
    panic!("Can't segment count item pair: '{s}'");
};

But really it’s the exact same as other languages, it just forces you to handle it better. C-based languages will return 0/null/-1 and you’ll have to check all 3 of those because they might not mean the same thing. How is that better?