Urban flood biophysical table with empty values raises cryptic error

[dcdenu4]

A few users have reported the following error when running the urban flood risk mitigation model:

07/07/2023 09:21:29  natcap.invest.utils WARNING  Empty or NaN values were found in the table: C:\Users\ddenu\Downloads\UrbanFloodMitigation\Biophysical_water_SF_empty_values.csv.
07/07/2023 09:21:29  natcap.invest.utils ERROR    Exception while executing natcap.invest.urban_flood_risk_mitigation
Traceback (most recent call last):
  File "scipy\sparse\_base.py", line 376, in asformat
  File "scipy\sparse\_coo.py", line 403, in tocsr
  File "scipy\sparse\_sputils.py", line 53, in upcast
TypeError: no supported conversion for types: (dtype('<U32'),)

This can happen when CN_[x] columns in the biophysical table have empty values. At the very least better error handling and messaging should be implemented. But with ongoing work to the Model Spec and CSV reading, maybe this is something that can be checked in a validation step.

Reported a few times on the forums:

• https://community.naturalcapitalproject.org/t/problems-in-the-biophysical-table-of-the-flood-risk-mitigation-model/3910
• https://community.naturalcapitalproject.org/t/urban-flood-mitigation-typeerror-no-supported-conversion-for-types-dtype-u32/3730