🐛 Fix some shexli warnings

Author: Schneegans

extension.js

@@ -769,10 +769,12 @@ export default class DesktopCube extends Extension {
     this._pressureBarrier.destroy();
     this._leftBarrier.destroy();
     this._rightBarrier.destroy();
+    this._pitch.destroy();
 
     this._pressureBarrier = null;
     this._leftBarrier     = null;
     this._rightBarrier    = null;
+    this._pitch           = null;
 
     // Clean up perspective correction.
     this._disablePerspectiveCorrection();

prefs.js

@@ -145,9 +145,10 @@ export default class DesktopCubePreferences extends ExtensionPreferences {
 
     // As we do not have something like a destructor, we just listen for the destroy
     // signal of our general page.
-    this._pages[0].connect('destroy', () => {
+    window.connect('close-request', () => {
       // Unregister our resources.
       Gio.resources_unregister(this._resources);
+      this._resources = null;
     });
   }