Hey eguiraud,
Sure thing, it will hopefully make ROOT a bit easier to use 
.
Yes, those branches are only present if mc is true.
This was actually supposed to be a work-around for something I reported before here, that missing branches can’t be skipped/ignored but generate a compiler error (which is a good thing, if there is a way to conditionally add Filters…).
So yes, some nicer compiler output would go a long way here, I think. Thanks for the extra detail on why that is, though .