Our QA team just got this crash in Xamarin Insights. I don't see any of our code in this except for the Main call, so maybe it's a Xamarin Forms bug? It would be nice if the NullReferenceException told us the object that was bad to help debug it:
System.NullReferenceExceptionObject reference not set to an instance of an object
Xamarin.Forms.Platform.iOS.NavigationRenderer.GetAppearedOrDisappearedTask(Page page)
Xamarin.Forms.Platform.iOS.NavigationRenderer.PopViewController(bool animated)
UIKit.UIApplication.UIApplicationMain(int, string[], intptr, intptr)(wrapper managed-to-native)
UIKit.UIApplication.Main(string[] args, IntPtr principal, IntPtr delegate)UIApplication.cs:74
UIKit.UIApplication.Main(string[] args, string principalClassName, string delegateClassName)UIApplication.cs:57
APPNAME.iOS.Application.Main(string[] args)Main.cs:17
Update: we are using Xamarin Forms 1.5.0.6447