I checked the code, you have fallen into what would appear to be a rare case where the player has been killed in the time you clicked the Attack button. I realize you normally would get the "bounty no longer available" message but it is also possible to get the message you posted when the player is on the bounty list when you are starting the attack action but is dead by the time the damage is going to take place. We are talking about fractions of a second here.
