in lime_tabular, the input argument feature_names cannot be None

[SarahAlidoost]

in lime_tabular, None is set as a default value for the input argument feature_names, see here. Later, the variable self.num_features is calculated as len(feature_names) which does not work on NoneType data, see here. Note in lime, self.num_features is not optional.

The same issue for the input argument class_names with the default value None.

For both input arguments, the default values should not be None or the None case should be handled inside the function.