Time: 0:00
Test a custom input to verify an edge case (e.g. empty lists, negative numbers, duplicates).
This bug belongs to the logic errors pattern
The wrong operator, an inverted condition, a formula the right way round but backwards.
What went wrong: Standard bracket notation array[-1] looks for an object key named '-1', which does not exist, returning undefined.
The fix: Use Array.prototype.at(-1) to safely access elements from the end of an array: breadcrumbs.at(-1)
Remember: In JavaScript, use array.at(-1) rather than array[-1] for negative indexing.
The pattern behind it: logic errors.
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<iframe src="https://trybughunt.com/embed/22414f98-9fa3-476b-a55c-f7f0a4e23e21" title="Debugging challenge: Accessing last element with negative index returns undefined" 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/22414f98-9fa3-476b-a55c-f7f0a4e23e21">TryBugHunt</a></p>