add loggings to detect min(NaN)

mlair/plotting/postprocessing_plotting.py

@@ -622,10 +622,13 @@ class PlotSectorialSkillScore(AbstractPlotClass):  # pragma: no cover
         self._labels = None
         self._model_name_for_plots = model_name_for_plots
         self._data, self._reference_model = self._prepare_data(data)
+        logging.info("PlotSectorialSkillScore: finished _prepare_data(data)")
         self._plot()
+        logging.info("PlotSectorialSkillScore: finished _plot()")
         self._save()
         self.plot_name = self.plot_name + "_vertical"
         self._plot_vertical()
+        logging.info("PlotSectorialSkillScore: finished _plot_vertical()")
         self._save()
 
     @TimeTrackingWrapper