Thanks to a comment from Claus, I’ve discovered the wonderful fact that null is not permitted as a key in an IDictionary in .NET. As it happens, the main problem was that I’d not covered namespaceless classes in NDocProc at all gracefully, but nonetheless, forbidding nulls as dictionary keys is a strange design decision.
I’ve fixed the bug, and now NDocProc handles types with no namespace much more gracefully. I’ve updated the repository:
hg clone http://hg.opensource.lshift.net/ndocproc
and there’s a snapshot (source and binary) available, as well: ndocproc-200801211208.zip