Fix: Don't affect (or interact with) panel of unlock screen

The panel gets set to the state it should have for the unlock screen
before extension disable. Because of this the extension makes icons
show, which shouldn't show. So fix that by not ordering the panel, if
the current session mode isn't "user".
Also generally don't interact with the panel, if the current session
mode isn't "user".

src/extensionModules/BoxOrderManager.js

@@ -184,6 +184,11 @@ var BoxOrderManager = GObject.registerClass({
      * bar to the correct box orders.
      */
     saveNewTopBarItems() {
+        // Only run, when in "user" session mode.
+        if(Main.sessionMode.currentMode !== "user") {
+            return;
+        }
+
         // Load the configured box orders from settings.
         const boxOrders = {
             left: this.#settings.get_strv("left-box-order"),