I'm assuming that the file in "1. Create a separate module with all the shared staff:" is called Config in part 2 which strikes me as odd.... perhaps a typo in "(Config::GLOB_DEBUG_MODE)"? I'm still sorta trying to figure this out. But my confusion says that perhaps "(Common::GLOB_DEBUG_MODE)" is what you meant?
If that is the case you have helped me out greatly!
Update: After looking over the rest of the replies I think that probably is the case, but massive brownie points for responding 99% perfectly in under 2 minutes of me posting