_clearTransformations does check if the sceneRef is null

[nohorjo]

When popping to route, _clearTransformations sets some props on a scene but unlike other places it does not perform a null check, causing the following error:

Fatal Exception: com.github.aoriani.rnstacktracer.ReactNativeException: null is not an object (evaluating 'this._sceneRefs[t].setNativeProps')
       at ._clearTransformations._clearTransformations(1621:7328)
       at .popN.popN(1621:14274)
       at .popToRoute.popToRoute(1621:15312)

[Desintegrator]

@nohorjo Does your commit work well? Don't u face some other issues because of that?

[nohorjo]

@Desintegrator My commit works for me and I have not experienced any other issues since. However, I've since been using react-navigation so I no longer use this component