BF: do or to "" to ensure that we do not end up treating None as str

[yarikoptic]

We started to get a test in dandi-cli to error out

E     +     '"/opt/hostedtoolcache/Python/3.12.1/x64/lib/python3.12/site-packages/nwbinspector/nwbinspector.py", '
E     +     'line 632, in _intercept_in_vitro_protein\n'
E     +     '    and getattr(subject, "subject_id", "").startswith("protein")\n'
E     +     '        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^\n'
E     +     "AttributeError: 'NoneType' object has no attribute 'startswith'\n",

I didn't test yet but this I think should fix it

[CodyCBakerPhD]

@yarikoptic I saw the DANDI alerts, but you beat me to the fix

Added changelog and test

[CodyCBakerPhD]

I will note that we test all PRs against DANDI dev to avoid these kinds of events: https://github.com/NeurodataWithoutBorders/nwbinspector/blob/dev/.github/workflows/dandi-dev.yml

@yarikoptic @jwodder Any idea why it was passing with flying colors on the original PR? #431 (actions run: https://github.com/NeurodataWithoutBorders/nwbinspector/actions/runs/7760160049/job/21165767343)

[jwodder]

@CodyCBakerPhD You're running dandi's tests through tox, which builds a fresh virtualenv and installs packages from PyPI, ignoring whatever dev version of nwbinspector you've installed outside of tox. Instead of using tox, invoke pytest directly.