include 'stagger' fix as cdo removed empty attrs

mlair/data_handler/data_handler_wrf_chem.py

@@ -255,6 +255,12 @@ class BaseWrfChemDataLoader:
             u_target_field = self._data[mapping_of_stag2unstag[u_stag_name]]
             v_target_field = self._data[mapping_of_stag2unstag[v_stag_name]]
 
+            # This if statements are needed as cdo might have removed empty attrs from variables
+            if "stagger" not in u_staged_field.attrs:
+                u_staged_field.attrs['stagger'] = ""
+            if "stagger" not in v_staged_field.attrs:
+                v_staged_field.attrs['stagger'] = ""
+
             u_stagger = u_staged_field.attrs['stagger']
             v_stagger = v_staged_field.attrs['stagger']