cpprest.natvis broken with VS2015 #7

Ported from CodePlex discussion: https://casablanca.codeplex.com/discussions/646435
As per bsergeev:

I am trying to use cpprest.natvis in VS2015 to look at the value in web::json::value variable, but I'm getting this error:
Natvis: C:\Program Files (x86)\Microsoft Visual Studio 14.0\Common7\Packages\Debugger\Visualizers\cpprest.natvis(168,68): Error: a pointer to a bound function may only be used to call the function
Error while evaluating '(_((web::json::details::Number)((m_value).Myptr))).m_number' in the context of type 'XXX.dll!web::json::value'.
The error is about checking the m_kind:


{(((web::json::details::Number)((m_value)._Myptr))).m_number}

It looks like web::json::value::Number is correct description of an element of web::json::value_type enum, so, what's the problem here?

Are all you guys in Casablanca team working in Linux and nobody is using VS2015? It's not that bad, check it out! :-)