Native client crashes when referencing widget excluded from layout

### Problem description

When referencing a widget excluded from the layout, the native iOS client crashes.

### Expected behavior

When an edge references a widget that is excluded from layout, it should fall back to `0`, similarly to what happens when the referenced widget is not appended to the widget tree at all.

### Environment

- Tabris.js version: 3.8, nightly
- OS: iOS

### Code snippet

```js
import {Composite, contentView} from 'tabris';

contentView.append(
<$>



);
```