[processing] Call toolbox.deleteLater to avoid slot calls after unload

Author: arnaud-morvan

python/plugins/processing/ProcessingPlugin.py

@@ -253,6 +253,7 @@ def unload(self):
         self.resultsDock.setVisible(False)
         self.iface.removeDockWidget(self.resultsDock)
 
+        self.toolbox.deleteLater()
         self.menu.deleteLater()
 
         # delete temporary output files