web: createInstancedAsset: "Cannot call gltfio$FilamentAsset._getAssetInstances due to unbound types: 0x19f231"

createInstancedAsset doesnt work from js

```js
const instancesArray: any[] = new Array(instanceCount).fill(null);
const asset = loader.createInstancedAsset(modelBuffer, instancesArray);
```

```
Cannot call gltfio$FilamentAsset._getAssetInstances due to unbound types: 0x19f231"
```

this may be a limitation of emscripten not being able to pass an array

however, according to the documentation in https://github.com/google/filament/blob/main/libs/gltfio/include/gltfio/AssetLoader.h#L204C20-L204C40 this is the only method to actually create multiple instances efficiently.