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: In Python, bool inherits directly from int (True == 1 and False == 0). isinstance(True, int) evaluates to True, causing True + 1 to compute 2.
The fix: Explicitly exclude booleans from the check: isinstance(val, int) and not isinstance(val, bool)
Remember: In Python, bool is an int subclass; always check not isinstance(val, bool) when strictly accepting integers.
The pattern behind it: type errors.
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<iframe src="https://trybughunt.com/embed/1cb6ae97-c670-45cb-bf33-ca953f026ced" title="Debugging challenge: Boolean argument passes integer check and increments to two" 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/1cb6ae97-c670-45cb-bf33-ca953f026ced">TryBugHunt</a></p>