If ReplayKit.StartBroadcasting() is called and a prompt asking to select an app to use for recording is dismissed, apps built with Mono2x crash on iOS.

Steps to reproduce:
1) Open the attached project.
2) Build for iOS using Mono2x.
3) Run on a device.
4) Press 'Start Broadcasting' UI button.
5) When a prompt, asking you to install or select a ReplayKit-compatible app appears, press 'Cancel'.

After a couple seconds, the app crashes in MonoStringNew(). This does not occur with IL2CPP.

Reproduced on:
5.6.0a2, 5.5.0b11, 5.4.2p4

Device tested:
iPhone 7 iOS 10.2