Time: 0:00
Test a custom input to verify an edge case (e.g. empty lists, negative numbers, duplicates).
This bug belongs to the type errors pattern
Totals that concatenate, sorts that put 10 before 9, comparisons that refuse to run.
What went wrong: for...in gives the indexes as text, "0", "1" and "2". Adding text joins them, so you get "0012".
The fix: for (const n of nums) { total += n; }
Remember: for...of for arrays, for...in for object keys.
The pattern behind it: type errors.
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<iframe src="https://trybughunt.com/embed/5a1f0a44-74c4-4f23-9f26-dc70f7508db0" title="Debugging challenge: Array sum returns 0012" width="100%" height="580" loading="lazy" style="border:1px solid #d4d4d8;border-radius:12px;max-width:760px"></iframe>
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