when destroying an asset, remove/destroy instances before destroying the parent asset

thermion_dart/lib/src/filament/src/implementation/ffi_filament_app.dart

@@ -263,6 +263,15 @@ class FFIFilamentApp extends FilamentApp<Pointer> {
   ///
   Future destroyAsset(covariant FFIAsset asset) async {
     await asset.removeAnimationComponent();
+    if (!asset.isInstance) {
+      for (final instance in (await asset.getInstances()).cast<FFIAsset>()) {
+        await instance.removeAnimationComponent();
+        await withVoidCallback((requestId, cb) =>
+            SceneAsset_destroyRenderThread(instance.asset, requestId, cb));
+        await instance.dispose();
+      }
+    }
+
     await withVoidCallback((requestId, cb) =>
         SceneAsset_destroyRenderThread(asset.asset, requestId, cb));
     await asset.dispose();