I have a doubt, the rules say nothing about the case when you only have one card remaining and therefore you cannot go to the mine. Do I have to discard that card at the end of my turn or it's carried over to the next one? In that case, How many cards do I draw? 4 cards or 5 independantly of what I have on my hand?

As the rules say that the player deck is emptied every 3 turns I assumed I have to end the turn with 0 cards, no matter if I use them or not.