Persistent toolbars error handling

Improved handling of potential (future) issues concerning Python based toolbars in Arch/Draft workbench.

Forum discussion:

https://forum.freecadweb.org/viewtopic.php?f=3&t=26256

src/Mod/Tux/PersistentToolbarsGui.py

@@ -28,7 +28,6 @@ conectedToolbars = []
 timer = QtCore.QTimer()
 mw = Gui.getMainWindow()
 
-
 def pythonToolbars():
     """Manage Python based toolbars in Arch and Draft workbench."""
 
@@ -36,9 +35,17 @@ def pythonToolbars():
 
     if active == "DraftWorkbench" or active == "ArchWorkbench":
         if hasattr(Gui, "draftToolBar"):
-            Gui.draftToolBar.Activated()
+            try:
+                Gui.draftToolBar.Activated()
+            except:
+                m = "Persistent toolbars: draftToolBar toolbar not managed.\n"
+                App.Console.PrintMessage(m)
         if hasattr(Gui, "Snapper"):
-            Gui.Snapper.show()
+            try:
+                Gui.Snapper.show()
+            except:
+                m = "Persistent toolbars: Snapper toolbar not managed\n."
+                App.Console.PrintMessage(m)
     else:
         pass