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: issubclass() raises a TypeError if its first argument is not a class type.
The fix: Verify that cls_obj is a type before checking subclass status: isinstance(cls_obj, type) and issubclass(cls_obj, Exception)
Remember: In Python, issubclass() requires class arguments; check isinstance(cls, type) first when handling arbitrary inputs.
The pattern behind it: type errors.
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