Handle missing and non-string CF axis units

Guard CF axis-unit parsing against missing and non-string values and keep the upstream dataset decode regression test while rebasing onto current main.

Author: Zaczero

pyresample/test/test_utils/test_cf.py

@@ -273,6 +273,26 @@ def test_load_cf_latlon(self, file_func, kwargs, exp_lat, exp_lon, future_geomet
         _validate_lonlat_cf_area(adef, cf_info, exp_lon, exp_lat)
         assert_future_geometry(adef, future_geometries)
 
+    def test_load_cf_axis_without_units(self):
+        cf_file = _prepare_cf_nh10km()
+        del cf_file['xc'].attrs['units']
+        del cf_file['yc'].attrs['units']
+
+        _, cf_info = load_cf_area(cf_file, variable='ice_conc')
+
+        assert cf_info['x']['unit'] is None
+        assert cf_info['y']['unit'] is None
+
+    def test_load_cf_axis_with_non_string_units(self):
+        cf_file = _prepare_cf_nh10km()
+        cf_file['xc'].attrs['units'] = 1
+        cf_file['yc'].attrs['units'] = 1
+
+        _, cf_info = load_cf_area(cf_file, variable='ice_conc')
+
+        assert cf_info['x']['unit'] is None
+        assert cf_info['y']['unit'] is None
+
     def test_load_cf_dataset_input_decodes_cf_coordinates(self, tmp_path):
         import xarray as xr
 

pyresample/utils/cf.py

@@ -167,8 +167,7 @@ def _load_cf_axis_info(nc_handle, coord_varname):
         unit = None
 
     # some units that are valid in CF are not valid to pass to proj
-    if unit.startswith('rad') or \
-       unit.startswith('deg'):
+    if not isinstance(unit, str) or unit.startswith(('rad', 'deg')):
         unit = None
 
     # return in a dictionnary structure