Dont worry, it's not a stupid choice at all. Bit unusual, but imo traps offer quite a few great debuff options as well as calltrops to keep the mobs in your awesome (AoE) carnage 
Fire/dark is sweet too and so are many many other combo's.
Bottomline will be no surprise: Go for it if you like the combo. And you'll also be a rarity - if that worth something to you
Just made my 1st Corupter and got to 7th.
Wondering if I have made a stupid choice of powers?
Should I really think about rerolling as Fire/Dark?