Was playing against platinum arena (coincidentally, my own arena deck) and had the following scenario occur:
With exactly 0 cards remaining in my deck, the AI cast Nightmare, filling my hand. On my turn, I should have been prevented from drawing because I had 8 cards in my hand, but as you can see from the screenshot, I lost the game even though I didn't draw a card. (I'd have lost the turn after in any event)
I strongly suspect, based on my own computer programming knowledge, that this bug is caused by the same problem that causes you to lose to deckout due to shard of bravery one turn early as well.