Well, that fragment doesn't compile, $net_grammar doesn't exist. so you didn't get that error message from there ;)

Using strict and warnings will help spot lots of these problems.

But, in general you're trying too hard, you've got to let the parser do what it's best at. It will handle all of that whitespace for you. Just (!) extend you grammar to handle all of the different sections and lets the parser do it's thing.

Maybe you need to review your parser theory and try out some simple examples first to get the hang of how RecDecent works. It is big and complex, and I don't use it often enough to keep all of the details in my head. I always have to experiment around a bit to get it to do what I want.

Have Kicad published a formal grammar for their file format? It's worth a look anyway.