Stability: null out destroyed actors

Acting on destroyed actors crashes 3.32 so make sure to null out references.

liveAltTab.js

@@ -103,6 +103,7 @@ class LiveAltTab extends AltTab.WindowSwitcherPopup {
         let to = this._switcherList.windows[num];
 
         this.clone && this.clone.destroy();
+        this.clone = null;
 
         let actor = to.get_compositor_private();
         let frame = to.get_frame_rect();
@@ -152,8 +153,10 @@ class LiveAltTab extends AltTab.WindowSwitcherPopup {
             transition: 'easeInOutQuad',
             onComplete: () => {
                 this.fog.destroy();
+                this.fog = null;
                 // this.space.cloneContainer.remove_effect(this.blur);
                 this.clone && this.clone.destroy();
+                this.clone = null;
                 this.space.moveDone();
             }
         });

minimap.js

@@ -288,5 +288,6 @@ class Minimap extends Array {
         this.signals.destroy();
         this.splice(0,this.length);
         this.actor.destroy();
+        this.actor = null;
     }
 }

navigator.js

@@ -171,6 +171,7 @@ var ActionDispatcher = class {
             Mainloop.source_remove(this._noModsTimeoutId);
         Main.popModal(this.actor);
         this.actor.destroy();
+        this.actor = null;
         // We have already destroyed the navigator
         !this._destroy && this.navigator.destroy();
     }

stackoverlay.js

@@ -143,8 +143,10 @@ class ClickOverlay {
         for (let overlay of [this.left, this.right]) {
             let actor = overlay.overlay;
             overlay.signals.destroy();
-            if (overlay.clone)
+            if (overlay.clone) {
                 overlay.clone.destroy();
+                overlay.clone = null;
+            }
             actor.destroy();
             overlay.removeBarrier();
         }
@@ -175,8 +177,10 @@ var StackOverlay = class StackOverlay {
         this.signals = new utils.Signals();
         this.signals.connect(overlay, 'button-release-event', () => {
             Main.activateWindow(this.target);
-            if (this.clone)
+            if (this.clone) {
                 this.clone.destroy();
+                this.clone = null;
+            }
             return true;
         });
 
@@ -197,8 +201,10 @@ var StackOverlay = class StackOverlay {
         if ("_previewId" in this)
             return;
         this._previewId = Mainloop.timeout_add(100, () => {
-            if (this.clone)
+            if (this.clone) {
                 this.clone.destroy();
+                this.clone = null;
+            }
 
             let [x, y, mask] = global.get_pointer();
             let actor = this.target.get_compositor_private();
@@ -230,7 +236,7 @@ var StackOverlay = class StackOverlay {
             return;
 
         this.clone.destroy();
-        delete this.clone;
+        this.clone = null;
         let space = Tiling.spaces.spaceOfWindow(this.target);
         // Show the WindowActors again and re-apply clipping
         space.moveDone();
@@ -290,9 +296,9 @@ var StackOverlay = class StackOverlay {
 
     setTarget(space, index) {
 
-        if (this.clone && this.clone.mapped) {
+        if (this.clone) {
             this.clone.destroy();
-            delete this.clone;
+            this.clone = null;
         }
 
         let bail = () => {

tiling.js

@@ -1047,8 +1047,11 @@ class Space extends Array {
     destroy() {
         this.signals.destroy();
         this.background.destroy();
+        this.background = null;
         this.cloneContainer.destroy();
+        this.cloneContainer = null;
         this.clip.destroy();
+        this.cloneContainer = null;
         let workspace = this.workspace;
     }
 }
@@ -1267,8 +1270,10 @@ class Spaces extends Map {
                 let actor = metaWindow.get_compositor_private();
                 actor.remove_clip();
 
-                if (metaWindow.clone)
+                if (metaWindow.clone) {
                     metaWindow.clone.destroy();
+                    metaWindow.clone = null;
+                }
 
                 if (metaWindow.get_workspace() === workspaceManager.get_active_workspace()
                     && !metaWindow.minimized)
@@ -1287,6 +1292,7 @@ class Spaces extends Map {
         }
 
         this.spaceContainer.destroy();
+        this.spaceContainer = null;
     }
 
     workspacesChanged() {
@@ -1838,8 +1844,10 @@ function remove_handler(workspace, meta_window) {
     let actor = meta_window.get_compositor_private();
     if (!actor) {
         signals.disconnect(meta_window);
-        if (meta_window.clone && meta_window.clone.mapped)
+        if (meta_window.clone && meta_window.clone.mapped) {
             meta_window.clone.destroy();
+            meta_window.clone = null;
+        }
     }
 }