Improve errorhandling on unsupported datatypes

[theyd]

Hi,

i had some struggle with the FromModel method using Tomlyn with VB.net

I created a TomlTable and added some datafields. One of the datafields had the type Net.IPAddress.
When i run the FromModel method, i got a very general exception of type System.Reflection.TargetInvocationException with the errormessage "Exception has been thrown by the target of an invocation".

I was able to fix the issue as i use string instead of IPAddress, but it took some time to get it.

Maybe a typecheck with an appropriate exception would help to understand what happened.