Time: 0:00
Test a custom input to verify an edge case (e.g. empty lists, negative numbers, duplicates).
This bug belongs to the null and undefined errors pattern
Cannot read properties of undefined, NoneType has no attribute, NaN appearing from nowhere.
What went wrong: Destructuring default values only trigger when a property is undefined, not when it is null. null * 2 evaluates to 0 in JavaScript.
The fix: Use the nullish coalescing operator to handle both null and undefined: config.maxRetries ?? 5
Remember: In JavaScript destructuring, default values ({ x = default }) do not apply to null.
The pattern behind it: null and undefined errors.
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<iframe src="https://trybughunt.com/embed/ccdc9872-98bd-4f3a-88d5-83c89010e161" title="Debugging challenge: Destructuring default value skipped when property is null" 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/ccdc9872-98bd-4f3a-88d5-83c89010e161">TryBugHunt</a></p>