QML engine crashes when running MomentJS code

I have adapted the MomentJS [1] library to work inside the QML interpreter. However, it crashes very early when running. I attach the crash-log and the adapted library.

[1] http://momentjs.com/

Thanks a lot!

PS. Question to V4 engineers: are there any plans to make QML ECMAScript compliant, so external libraries can run un-changed? It would be so awesome to be able to reuse JS libraries without this kind of effort, which it seems I am not the only one doing (https://github.com/jnetterf/underscore-qml).