SLType.cs Not Checking For Null AssociatedTypePath

[tj-devel709]

This PR introduced this change:

var name = IsMetatype ? (Name + ".Type") : AssociatedTypePath.Any () ? Name + $".{AssociatedTypePath.FirstOrDefault ()}" : Name;

which does not check if AssociatedTypePath is null.
This is causing some tests to fail including tests inside SwiftReflector.GenericStructTests.