Dying to a boss AFTER the fight ends - still get rewards, but can lose items

It is possible to die to The Wither after the fight ends. You can still take damage from the Wither effect and die. I'm unsure if this can occur from the other bosses. If this occurs, I'm pretty sure you still get the rewards (Boss key + money), but your items drop when you die. I tend to think that either taking damage after the boss dies should be disabled, or the fight shouldn't be "over" (i.e. the winning message/rewards) until after you get teleported out of the arena and are safe from death. Not sure if this should be considered a bug, but I actually witnessed this happen to another player