# T08: Failing Test Diagnosis

First run `python3 -m unittest discover -s tests_t08 -v` to reproduce the failure provided with the task. Then locate the root cause in the production code and fix it. Do not delete, skip, weaken assertions in, or rename `tests_t08/test_csv_import.py`, do not modify its test data, and do not merely catch the error to make the test "go green".

After the fix, rerun the same command, then run `python3 -m unittest discover -s tests -v`. Finally explain the root cause, where you changed code, and the actual results of both commands; add no runtime dependencies.