I failed to copy a key line from SNCL.py (and I failed to notice because I neglected to run unit tests again before committing).

I neglected to run unit tests before the previous commit, and failed to notice that a returned variable could possibly be undefined. Fixed.

There is an ambiguity that exists between `data_type` and `location` in *SNCL.py. Ideally, we'd clean this up, but that involves many changes, and well beyond just the *SNCL.py files. These changes at least fix issues with geomagio scripts that popped up during testing.