No IntelliPrompt error for unknown types

Hi Sergey,

The .NET Languages Add-on contains a parser that will report syntax errors but it does not have a compiler in it, which would be necessary to detect unknown types.  You could possibly build a custom IParser language service that calls our default IParser implementation (like CSharpParser), and also calls into a third-party compiler to detect things like this and report them in the returned parse data's Errors collection, part of the IParseErrorProvider interface for parse data.  That would allow squiggle lines to show for anything the compiler detected.