DEM.to_vref fails if CRS does not have an EPSG code

[adehecq]

When running the command my_dem.to_vref('WGS84'), it fails with the following error:

~/development/GlacioHack/xdem/xdem/dem.py in ccrs(self)
146 with warnings.catch_warnings():
147 warnings.filterwarnings("ignore", module="pyproj")
--> 148 self._ccrs = pyproj.Proj(init="EPSG:" + str(int(crs.to_epsg())), geoidgrids=self.vref_grid).crs
149 else:
150 self._ccrs = None

TypeError: int() argument must be a string, a bytes-like object or a number, not 'NoneType'

This is because in that case, my_dem.crs.to_epsg() returns None. The CRS of that DEM was set with a proj4 string and never with an EPSG code, so gdal probably does not find it.

You can reproduce the error by reprojecting the xdem sample DEM in a different projection e.g.,:

import geoutils as gu
import matplotlib.pyplot as plt
import xdem

reference_dem = xdem.DEM(xdem.examples.get_path("longyearbyen_ref_dem"))
test_dem = reference_dem.reproject(dst_crs='+proj=aea +lat_0=30 +lon_0=95 +lat_1=15 +lat_2=65 +x_0=0 +y_0=0 +datum=WGS84 +units=m +no_defs=True')
test_dem.set_vref('EGM08')
test_dem.to_vref('WGS84')
# -> Fails
reference_dem.set_vref('EGM08')
reference_dem.to_vref('WGS84')
# -> works