No legend displayed in plots of evaluation #38
Description
Something is wrong with the legend in "EV_Energy_Level.png" plotted by 'plot_comparable_EV_SoC' in 'evaluator_plot.py'. No legend is displayed when the last subplot is empty, and it raises an warning:
ev2gym/visuals/evaluator_plot.py:550: UserWarning: No artists with labels found to put in legend. Note that artists whose label start with an underscore are ignored when legend() is called with no argument.