Bug 1599875 - handle cases where async operations within the accessibility related actors run while the actors get destroyed. r=nchevobbe

Depends on D55145

Differential Revision: https://phabricator.services.mozilla.com/D55146

--HG--
extra : moz-landing-system : lando

devtools/server/actors/accessibility/accessible.js

@@ -193,7 +193,7 @@ const AccessibleActor = ActorClassWithSpec(accessibleSpec, {
   },
 
   get isDestroyed() {
-    return this.actorID == null;
+    return this.walker == null || this.actorID == null;
   },
 
   get role() {
@@ -369,6 +369,10 @@ const AccessibleActor = ActorClassWithSpec(accessibleSpec, {
     }
 
     const doc = await this.walker.getDocument();
+    if (this.isDestroyed) {
+      // This accessible actor is destroyed.
+      return relationObjects;
+    }
     relations.forEach(relation => {
       if (RELATIONS_TO_IGNORE.has(relation.relationType)) {
         return;
@@ -475,6 +479,10 @@ const AccessibleActor = ActorClassWithSpec(accessibleSpec, {
       appliedColorMatrix: this.walker.colorMatrix,
     });
 
+    if (this.isDestroyed) {
+      // This accessible actor is destroyed.
+      return null;
+    }
     walker.restoreStyles(win);
 
     return contrastRatio;

devtools/server/actors/accessibility/audit/keyboard.js

@@ -23,6 +23,12 @@ loader.lazyRequireGetter(
   "nodeConstants",
   "devtools/shared/dom-node-constants"
 );
+loader.lazyRequireGetter(
+  this,
+  "isDefunct",
+  "devtools/server/actors/utils/accessibility",
+  true
+);
 
 const {
   accessibility: {
@@ -483,6 +489,9 @@ function tabIndexRule(accessible) {
 }
 
 function auditKeyboard(accessible) {
+  if (isDefunct(accessible)) {
+    return null;
+  }
   // Do not test anything on accessible objects for documents or frames.
   if (
     accessible.role === Ci.nsIAccessibleRole.ROLE_DOCUMENT ||