Do you understand the reason they don't use exceptions(because it would conflict to much with their older non-exception code)?
They even state that projects which do not need to tie into their existing systems are free to use exceptions, and that given their time again, they would prefer to use exceptions everywhere.
Just keep in mind, some of the stuff in their guide really doesn't apply to anyone but Google.
Not that it makes a difference for SMFL anyway. Just some food for thought encase you would otherwise want to use exceptions.