[3pt] Datum error handling in stage-based CatFIM

[EmilyDeardorff]

In the logs from stage-based CatFIM versions 4.8.6.1 and 4.8.7.2, the following error appears multiple times:

2025-07-11 22:25:48 | ERROR     || ERROR: 17100202 : fsso3: ngvd_to_navd_ft
2025-07-11 22:25:48 | ERROR     || Traceback (most recent call last):
  File "/foss_fim/tools/catfim/generate_categorical_fim.py", line 1366, in __adjust_datum_ft
    datum_adj_ft = ngvd_to_navd_ft(datum_info=datum_data)
  File "/foss_fim/tools/tools_shared_functions.py", line 1352, in ngvd_to_navd_ft
    message = results['message']
UnboundLocalError: local variable 'results' referenced before assignment

Update the code so that the error gets caught and explained in a more legible way.

I have a hunch that the Vdatum call isn't producing an output for these sites, but it will be good to confirm either way.

[RobHanna-NOAA]

When we make a change to the tools_shared_functions, keep an eye on other scripts to make sure we don't break them. We don't need to test them all, but maybe one or two to make sure they are happy .