rustNull / UndefinedEasy

Empty slice first element unwrap panic

Time: 0:00

BugFind the bug and fix the code

What it should do

Get first element of slice, or return -1 if empty. Example: get_first_slice_element([]) -> -1

What happens instead

panicked at 'called `Option::unwrap()` on a `None` value' on empty slice

fn get_first_slice_element(nums: Vec<i32>) -> i32 {
    // Calling .first().unwrap() panics when nums is empty
    *nums.first().unwrap()
}

fn main() {
    println!("{}", get_first_slice_element(vec![]));
}

Test a custom input to verify an edge case (e.g. empty lists, negative numbers, duplicates).

⏱️0:00

Hints

🏆 0 hints = Flawless Solve

Think & Test Cooldown

2:00 remaining

Take a moment to read the bug symptom and trace the code with Run & Check before unlocking Hint 1.

Hint 2

Unlocks after Hint 1

Hint 3

Unlocks after Hint 2

This bug belongs to the null and undefined errors pattern

Cannot read properties of undefined, NoneType has no attribute, NaN appearing from nowhere.

Learn the null and undefined errors pattern Step through your own code

<iframe src="https://trybughunt.com/embed/630d40bf-1c12-486b-b205-71ecbb9d7878" title="Debugging challenge: Empty slice first element unwrap panic" width="100%" height="580" loading="lazy" style="border:1px solid #d4d4d8;border-radius:12px;max-width:760px"></iframe> <p style="font-size:14px">Debugging challenge from <a href="https://trybughunt.com/challenges/630d40bf-1c12-486b-b205-71ecbb9d7878">TryBugHunt</a></p>

fn get_first_slice_element(nums: Vec<i32>) -> i32 { // Calling .first().unwrap() panics when nums is empty *nums.first().unwrap() } fn main() { println!("{}", get_first_slice_element(vec![])); }

Empty slice first element unwrap panic

What it should do

What happens instead

More null and undefined errors to practise

Related errors

Empty slice first element unwrap panic

What it should do

What happens instead

More null and undefined errors to practise

Related errors