If your opponent's turn ends and you have only one card left in your deck, the game is still on. You can still draw a card, so do that.
If at any time during your turn you have zero cards in your deck, you haven't lost yet. There's no rule that says you lose if you have no cards in your deck during your turn.
Once your turn ends, you still haven't lost. If you opponent does anything to put cards back in your deck (like Rocket's Admin), you've just been saved.
The only time you lose with no cards in your deck is if it's the start of your turn and you can't draw a card from your deck.