Fix Entity#destroy

src/framework/entity.js

@@ -514,34 +514,13 @@ class Entity extends GraphNode {
             this.c[name].enabled = false;
         }
 
+        super.destroy();
+
         // Remove all components
         for (const name in this.c) {
             this.c[name].system.removeComponent(this);
         }
 
-        // Detach from parent
-        if (this._parent)
-            this._parent.removeChild(this);
-
-        // recursively destroy all children
-        const children = this._children;
-        while (children.length) {
-
-            // remove a child from the array and disconnect it from the parent
-            const child = children.pop();
-            child._parent = null;
-
-            if (child instanceof Entity) {
-                child.destroy();
-            }
-        }
-
-        // fire destroy event
-        this.fire('destroy', this);
-
-        // clear all events
-        this.off();
-
         // remove from entity index
         if (this._guid) {
             delete this._app._entityIndex[this._guid];

src/framework/scene-registry.js

@@ -376,14 +376,16 @@ class SceneRegistry {
         const app = this._app;
 
         const onBeforeAddHierarchy = (sceneItem) => {
-            // Destroy/Remove all nodes on the app.root
-            const rootChildren = app.root.children;
-            while (rootChildren.length > 0) {
-                const child = rootChildren[0];
-                child.reparent(null);
-                child.destroy?.();
+            // Destroy all nodes on the app.root
+            const { children } = app.root;
+            while (children.length) {
+                children[0].destroy();
             }
-
+            Debug.assert(
+                Object.keys(app._entityIndex).length === 0,
+                "Destroyed all entities but these entities survived:",
+                app._entityIndex
+            );
             app.applySceneSettings(sceneItem.data.settings);
         };
 

src/scene/graph-node.js

@@ -480,6 +480,37 @@ class GraphNode extends EventHandler {
         return this;
     }
 
+
+    /**
+     * Detach it from the hierarchy. Then recursively destroy all ancestors.
+     *
+     * @example
+     * const firstChild = this.entity.children[0];
+     * firstChild.destroy(); // delete child, all components and remove from hierarchy
+     */
+    destroy() {
+        // Detach from parent
+        this._parent?.removeChild(this);
+
+        // Recursively destroy all children
+        const children = this._children;
+        while (children.length) {
+            // Remove last child from the array
+            const child = children.pop();
+            // Disconnect it from the parent: this is only an optimisation step, to prevent calling
+            // GraphNode#removeChild which would try to refind it via this._children.indexOf (which
+            // will fail, because we just removed it).
+            child._parent = null;
+            child.destroy();
+        }
+
+        // fire destroy event
+        this.fire('destroy', this);
+
+        // clear all events
+        this.off();
+    }
+
     /**
      * Search the graph node and all of its descendants for the nodes that satisfy some search
      * criteria.