Fix overwriting in generic level check (#886)

Co-authored-by: Manuel Schlund <32543114+schlunma@users.noreply.github.com>

Author: sloosvel

esmvalcore/cmor/check.py

@@ -385,51 +385,54 @@ def _check_dim_names(self):
                                 self._does_msg, coordinate.name, 'exist')
 
     def _check_generic_level_dim_names(self, key, coordinate):
+        standard_name = None
+        out_name = None
+        name = None
         if coordinate.generic_lev_coords:
             for coord in coordinate.generic_lev_coords.values():
                 try:
                     cube_coord = self._cube.coord(
                         var_name=coord.out_name
                     )
-                    coordinate.out_name = coord.out_name
+                    out_name = coord.out_name
                     if cube_coord.standard_name == coord.standard_name:
-                        coordinate.standard_name = coord.standard_name
-                        coordinate.name = coord.name
+                        standard_name = coord.standard_name
+                        name = coord.name
                 except iris.exceptions.CoordinateNotFoundError:
                     try:
                         cube_coord = self._cube.coord(
                             var_name=coord.standard_name
                         )
-                        coordinate.standard_name = coord.standard_name
-                        coordinate.name = coord.name
+                        standard_name = coord.standard_name
+                        name = coord.name
                     except iris.exceptions.CoordinateNotFoundError:
                         pass
-            if coordinate.standard_name:
-                if not coordinate.out_name:
+            if standard_name:
+                if not out_name:
                     self.report_error(
-                        f'Coordinate {coordinate.name} '
+                        f'Generic level coordinate {key} '
                         'has wrong var_name.',
                     )
-                level = coordinate.generic_lev_coords[coordinate.name]
+                level = coordinate.generic_lev_coords[name]
                 level.generic_level = True
                 level.generic_lev_coords = self._cmor_var.coordinates[
                     key].generic_lev_coords
                 self._cmor_var.coordinates[key] = level
                 self.report_debug_message(
                     f'Generic level coordinate {key} '
                     'will be checked against '
-                    f'{coordinate.name} coordinate information'
+                    f'{name} coordinate information'
                 )
             else:
-                if coordinate.out_name:
+                if out_name:
                     self.report_critical(
-                        f'Coordinate {coordinate.name} '
+                        f'Generic level coordinate {key} '
                         'has wrong standard_name '
                         'or is not set.',
                     )
                 else:
                     self.report_critical(
-                        self._does_msg, coordinate.name, 'exist'
+                        self._does_msg, key, 'exist'
                     )
 
     def _check_coords(self):