iOS 7/8 issue with Ionic 2 app

My Ionic 2 app crashes on opening for my iOS 7 and iOS 8 users. Has anyone had anything similar happen and managed to find out why? My app is pretty basic - similar in structure to the Conference App i.e tabbed interface and some basic components. With iOS 9 it works ok. Currently using alpha40 version of Ionic 2.

Could be a version issue, for example in android ripple effects only works for version 5.0 up, though idk about an issue so big as to crash, you should fill an issue in github.

Thanks, I have logged it with the Ionic team, I just wondered if anyone had had similar problems and been able to get round it.