apply fix, /close #349

mlair/run_modules/post_processing.py

@@ -930,7 +930,7 @@ class PostProcessing(RunEnvironment):
                 model_list = None
 
             # test errors of competitors
-            for model_type in remove_items(model_list or [], list(errors.keys())):
+            for model_type in (model_list or []):
                 if self.observation_indicator not in combined.coords[self.model_type_dim]:
                     continue
                 if model_type not in errors.keys():