Merge pull request #280 from BiAPoL/fix_opacity_runtime_error

fix opacity adjustment and set it to low non-zero value

napari_clusters_plotter/_plotter.py

@@ -124,7 +124,7 @@ def manual_clustering_method(inside):
                 plot_cluster_name=clustering_ID,
             )
             if isinstance(self.analysed_layer, Labels):
-                self.layer_select.value.opacity = 0
+                self.layer_select.opacity = 0.2
 
         # Canvas Widget that displays the 'figure', it takes the 'figure' instance
         self.graphics_widget = MplCanvas(