BUG: crash when no competitor is provided

Bug

Error description

There is an error if no competitors is provided to MLAir but a model_display_name.

Error message

First guess on error origin

Error origin

In experiment_setup there is the check for duplicated naming of models as introduced in #366 (closed) but the check is not written properly as competitors can have None type.

Solution

class ExperimentSetup(RunEnvironment):
   ...
   def __init__(...):
      ...
      # set competitors
-     if model_display_name is not None and model_display_name in competitors:
+     if model_display_name is not None and competitors is not None and model_display_name in competitors: