Okay this is nice, trust me
The thing we’ve all come to love is bugged!
String.IsNullOrEmpty can throw a NullReferenceException at runtime in certain cases. The problem is with the optimizations performed by the the JIT compiler.
Microsoft already fixed this issue in the first beta, so all you early adapters can already enjoy the fixed String.IsNullOrEmpty 
Microsoft’s Feedback
Article demonstrating the issue
