Failure in test_list_item_mixed_print.py on macOS

[certik]

The released version in conda fails in test_list_item_mixed_print.py:

../integration_tests/test_list_item_mixed_print.py * runtime
The JSON metadata differs against reference results
Reference JSON: tests/reference/runtime-test_list_item_mixed_print-a3fd49f.json
Output JSON:    tests/output/runtime-test_list_item_mixed_print-a3fd49f.json
Omitting 9 identical items
Differing items:
{'stderr_hash': '9e014e97e6b24d4be0c537d9dc61d875cbc5cf7f73deb9c97779245a'} != {'stderr_hash': None}
{'stderr': 'runtime-test_list_item_mixed_print-a3fd49f.stderr'} != {'stderr': None}No reference stderr_hash available for ../integration_tests/test_list_item_mixed_print.py

Error: Process completed with exit code 1.

https://github.com/lcompilers/lpython-conda-testing/pull/6#issuecomment-2217148289

It doesn't happen at the CI. We need to investigate.

[Thirumalai-Shaktivel]

If the reference stderr is None and the generated stderr has some value, then we have to print it (using run_tests.py), I think.