Assert failure while trying to iterate fields

A new user question. BTW is there a search for old threads?

I’m getting the failure:

void clang::RecordDecl::LoadFieldsFromExternalStorage() const: Assertion `hasExternalLexicalStorage() && Source && “No external storage?”’ failed.

when trying to iterate over a RecordDecl and not sure even what’s going on let along how to deal with it:

I’m proceeding from the example in
http://clang.llvm.org/docs/LibASTMatchersTutorial.html

Here is some context:
https://gist.github.com/waTeim/8757662c445ce3b4084f

Thanks in advance for any help

-Jeff