Raise error when no gridded data is loaded

[scotthavens]

When loading a gridded dataset whose domain does not match the topo.nc domain, it will show that 0 cells within model domain but SMRF will continue on and try to interpolate. Suggest raising an error to alert users that their input data doesn't match the model domain.

[scotthavens]

HRRR
Just check if metadata is not empty.

smrf/smrf/data/hrrr_grib.py

Line 81 in 465d42c

metadata, data = wfr.data.hrrr.FileLoader(

WRF

smrf/smrf/data/wrf.py

Line 76 in 465d42c

self._logger.debug(

NetCDF

smrf/smrf/data/netcdf.py

Line 64 in 465d42c

self._logger.debug('{} grid cells within model domain'.format(len(a)))