In the list of Jungle Mimic's drops, there's a line that is about RegisterToNPC(NPCID.BigMimicJungle, ItemDropRule.Common(ItemID.GelBalloon, 3, 69)); (the last line of the Jungle Mimics drops)
This line causes an exception each time the Jungle Mimic tries to drop the Sparkle Slime Balloon as it...