Mismatch between MLD report and pytest results

Related to #766 (closed)

The number of "None" rows in the mld.csv report does not match the number of errors in the pytest report. E.g. looking at https://forge.3gpp.org/rep/sa4/audio/ivas-basop/-/pipelines/33981/test_report there are 10 errors in the ivas-pytest-mld-long-dec job, while the MLD report https://forge.3gpp.org/rep/sa4/audio/ivas-basop/-/jobs/269489/artifacts/file/mld.csv has 52 tests with "None" in the MLD and MAX ABS columns.

The number of passing tests matches the number of rows with 0 MLD difference (float code still present?), 88 test cases. The number of rows also matches the total number of test, excluding the skipped tests and errors, which are counted both under Failed and Errors in the pytest report.

Many of the tests with "None" in the MLD report come from tests/renderer/test_renderer.py, so it may still be related to #761 (closed).