Error messages appearing on screen while in game

it said exactly this and yes it said molang not mojang

[Molang][error]-minecraft:player.025e1d81d-7cb7-4fb8-bb0d-08ac06077835.Skin002 | binding expression q.item_slot_to_bone_name(c.item_slot) did not return a name?

that is waht it said, it happened only when my friend joined the game, and im not sure what update came out but we recently got the update where ambient sounds were added to the nether.