Bug 1602075 - display Inspect Accessibility Properties menu item in inspector if devtools.accessibility.auto-init.enabled pref is set to true. r=gl

Differential Revision: https://phabricator.services.mozilla.com/D71587

devtools/client/inspector/markup/markup-context-menu.js

@@ -393,8 +393,15 @@ class MarkupContextMenu {
     });
 
     // Only attempt to determine if a11y props menu item needs to be enabled if
-    // AccessibilityFront is enabled.
-    if (this.inspector.accessibilityFront.enabled) {
+    // AccessibilityFront is enabled or a11y panel auto init option is set to
+    // true.
+    if (
+      this.inspector.accessibilityFront.enabled ||
+      Services.prefs.getBoolPref(
+        "devtools.accessibility.auto-init.enabled",
+        false
+      )
+    ) {
       this._updateA11YMenuItem(showA11YPropsItem);
     }
 
@@ -952,9 +959,25 @@ class MarkupContextMenu {
   }
 
   async _updateA11YMenuItem(menuItem) {
-    const hasA11YProps = await this.walker.hasAccessibilityProperties(
-      this.selection.nodeFront
-    );
+    if (!this.walker?.actorID) {
+      return;
+    }
+
+    let hasA11YProps = false;
+    try {
+      hasA11YProps = await this.walker.hasAccessibilityProperties(
+        this.selection.nodeFront
+      );
+    } catch (e) {
+      // The walker might already be destroyed at this point. Only throw an
+      // exception when it is still alive and well.
+      if (this.walker?.actorID) {
+        throw e;
+      }
+
+      return;
+    }
+
     if (hasA11YProps) {
       const menuItemEl = Menu.getMenuElementById(menuItem.id, this.toolbox.doc);
       menuItemEl.disabled = menuItem.disabled = false;