Thank you very much for your nice comments and the bug report!
I'm looking into it right now but I'm wondering how you got yourself in that situation.
Do you happen to remember what was played before? Your card with Exhume 2 and then destroy 2 target Minions shouldn't be playable without Minions on the field to target. Do you remember if you were able to play it without Minions on the field? Or perhaps you played with minions still on the field but your enemy Repealed them in response?
It's okay if you don't remember, though! Thanks again!