A repeated error displays over the top of the screen which reads:

[Animation][error]-minecraft:player0.202539ce-e6c5-40b5-a4a1-4296277d18f6.Slimeef479b6d-7072-47aa-8985-0f025cd24cdb error: null animation for animation 2 of state first_person of wield

It covers half of the screen while in playtime, and although it is slightly transparent and playtime can continue, it is distracting to the player.