NoSuchMethodError: The method 'findRenderObject' was called on null. Receiver: null Tried calling: findRenderObject()

Version 1.0.1.
```
Non-fatal Exception: NoSuchMethodError: The method 'findRenderObject' was called on null.
Receiver: null
Tried calling: findRenderObject()
0  ???                            0x0 _getImageFromWidget + 232 (snappable.dart:232)
1  ???                            0x0 snap + 114 (snappable.dart:114)
```
Probably it was called after parent widget was disposed.