Bad sprite type

Edit: Just realized, wrong section, sorry.

So I own a Prop Hunt server and one of my co-owners just messaged me saying that his console is being spammed with

GetSpriteAxes: Bad sprite type 1853321060

Now, I’ve (sort of) narrowed this down to a player model, Amaterasu. Here’s my Pointshop code:

ITEM.Name = 'Amaterasu'
ITEM.Price = 3000
ITEM.Model = 'models/player_amaterasu.mdl'
ITEM.SubCategory = 'VIP Player Models'
ITEM.AllowedUserGroups = { "superadmin", "headadmin", "admin", "moderator", "operator", "trial", "vip+", "vip", "donator" }

function ITEM:OnEquip( ply, modifications )
  if not ply._OldModel then
    ply._OldModel = ply:GetModel()
  timer.Simple( 1, function()
    ply:SetModel( self.Model )
  end )

function ITEM:OnHolster( ply )
  if ply._OldModel then
    ply:SetModel( ply._OldModel )

function ITEM:PlayerSetModel( ply )
  ply:SetModel( self.Model )

And this is the Steam Workshop page:

Now, from the other topics I read on this forum, it seems it’s thought this is a Pinion error. I don’t, nor have ever, had Pinion on my server, nor any of my servers. I’m not sure if it happens with other player models, just that is the model he was using at the time. Does anyone know why this is happening? Or is it nothing to worry about?

I’ve tried to be as descriptive as possible, if you need more information, let me know.