workspace-indicator: Ignore 'e' press when already in edit mode

While events should already be consumed by the entry while editing,
it does not hurt to be explicit, so only process 'e' to enter edit
mode while not already in edit mode.

Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell-extensions/-/merge_requests/423>

extensions/workspace-indicator/workspaceIndicator.js

@@ -451,6 +451,9 @@ class EditableMenuItem extends PopupMenu.PopupBaseMenuItem {
             if (event.get_key_symbol() !== Clutter.KEY_e)
                 return Clutter.EVENT_PROPAGATE;
 
+            if (this._editButton.checked)
+                return Clutter.EVENT_PROPAGATE;
+
             this._editButton.checked = true;
             return Clutter.EVENT_STOP;
         });