Fix _recombine_columns when either geocolumn or non-geocolumn was emp…

…ty (#1438)

closes #1437

When `GeoDataFrame._split_out_geometry_columns` is called, there may be no geometry columns to split out into 2 DataFrames; therefore, once `GeoDataFrame._recombine_columns`, it assumed the 2 DataFrames were always non-empty. Added a check to bypass this validation if either was empty.

I ran the `ZipCodes_Stops_PiP_cuSpatial` notebook locally and the (non-commented) cells no longer raise an exception.

Authors:
  - Matthew Roeschke (https:/mroeschke)
  - James Lamb (https:/jameslamb)

Approvers:
  - Mark Harris (https:/harrism)

URL: #1438

python/cuspatial/cuspatial/core/geodataframe.py

@@ -168,7 +168,11 @@ def _recombine_columns(
 
  The output is meant for GeoDataFrame._from_data.
  """
- if not geo_columns.index.equals(data_columns.index):
+ if not (
+ geo_columns.empty
+ or data_columns.empty
+ or geo_columns.index.equals(data_columns.index)
+ ):
  raise ValueError("geo_columns.index must equal data_columns.index")
 
  columns_mask = self.columns