Pointshop Accessory Issue

[Sequax]

Recently my "Jump Pack" accessory suddenly stopped working.

Here's the default code for the jumppack that I'm currently using:

ITEM.Name = 'Jump Pack'
ITEM.Price = 1000
ITEM.Model = 'models/xqm/jetengine.mdl'
ITEM.Bone = 'ValveBiped.Bip01_Spine2'

function ITEM:OnEquip(ply, modifications)
	ply:PS_AddClientsideModel(self.ID)
end

function ITEM:OnHolster(ply)
	ply:PS_RemoveClientsideModel(self.ID)
end

function ITEM:ModifyClientsideModel(ply, model, pos, ang)
	model:SetModelScale(0.5, 0)
	pos = pos + (ang:Right() * 7) + (ang:Forward() * 6)
	
	return model, pos, ang
end

function ITEM:Think(ply, modifications)
	if ply:KeyDown(IN_JUMP) then
		ply:SetVelocity(ply:GetUp() * 6)
	end
end

Here's the error it's throwing:

[ERROR] addons/customps/lua/sv_player_extension.lua:234: attempt to call method 'OnBuy' (a nil value)
  1. PS_BuyItem - addons/customps/lua/sv_player_extension.lua:234
   2. func - addons/customps/lua/sv_pointshop.lua:4
    3. unknown - lua/includes/modules/net.lua:32

Lastly, here's what I have in my sv_player_extension file on line 234:

	ITEM:OnBuy(self)

This also randomly happened to the backpack that I had in my shop before, but I removed it as nobody was buying it anyways. The jumppack had been working fine up until today, but I haven't changed anything that would affect those files recently.

Additional Info:

I'm currently using the "Advanced Point Shop [PAC]" as my pointshop.