GetMethod sometimes returns null, causes an exception to be thrown

[Mitch Capper (they, them)]

GetMethod can return null (at least with release builds under UWP in certain cases). There is an Assert that catches this but in release builds this still can cause a crash.

Ben.Demystifier/src/Ben.Demystifier/EnhancedStackTrace.Frames.cs

Line 56 in 1ca8f79

 if (!ShowInStackTrace(method) && i < stackFrames.Length - 1) 

is the issue, as ShowInStackTrace requires it not to be null. The rest of the code is setup to handle null methods properly (it seems).

I believe the library should avoid throwing exceptions ever, as it is normally used for exception handling.

Will submit a PR.