If I understand you correctly, read more history. the nazis invaded Poland together with the USSR on two fronts (as, you know, best buds), hard to botch that.
When the nazis invaded France...it was the French who fucked up...the nazis didn't.
Ofc I know the Poland partition, but to call them best buds after what happened later? Stalin may have believed that, but for Hitler it was more a tactical gambit.
I know the french should've tried to stop them in the border mountains, but still that's not the point here. I understand we were discussing the international reaction to attacking a country.