Lua help Please?

I need some help with this code. i keep getting this error here. “ocrp\gamemode\vgui\item.lua:101] attempt to call method ‘RemoveItem’ (a nil value)”

Heres the whole function line for it.


function PANEL:PaintOver ( )    if !self:IsVisible() or self:GetAlpha() == 0 then return false; end


    if self.Type == TYPE_SHOP_LOCAL and GAMEMODE.ItemDatabase[self.MonitorItem].RestrictSelling then
        surface.SetDrawColor(255, 0, 0, 10);
        surface.DrawRect(0, 0, self:GetWide(), self:GetTall());
    end
    
    local IsTrade = self.Type == TYPE_TRADE_INVENTORY or self.Type == TYPE_TRADE_OFFER_LOCAL or self.Type == TYPE_TRADE_OFFER;


    
    if self.Type != TYPE_SHOP and !IsTrade then
        local Quantity = LocalPlayer():GetTable().RoleplayData.Items[self.MonitorItem] or 0;
        
        if Quantity == 0 then
            if self.Type == TYPE_LOCAL then
                GAMEMODE.InventoryPanel_ItemList:RemoveItem(self);
                GAMEMODE.InventoryPanel_ItemList:InvalidateLayout();
            else
                GAMEMODE.InventoryPanel_ShopItemList:RemoveItem(self);
                GAMEMODE.InventoryPanel_ShopItemList:InvalidateLayout();
            end
        end
        

If you can help please do so.

Im gonna take a long shot at this but RemoveItem may not exist.