Lua How can i prevent this error

[henkas]

Not sure how this happens but i assume its because maybe there is item that doesnt exist in the traders? But tracking it is just wild
Lua Script Error: [Npc interface]
(Unknown scriptfile)
data/npc/lib/npcsystem/modules.lua:1017: [ShopModule.onSell] items[itemid] == nil
stack traceback:
[C]: at 0x5555556bbdc0
[C]: in function 'error'
data/npc/lib/npcsystem/modules.lua:1017: in function 'callbackOnSell'
data/npc/lib/npcsystem/npchandler.lua:272: in function 'processModuleCallback'
data/npc/lib/npcsystem/npchandler.lua:476: in function 'onSell'
data/npc/lib/npcsystem/modules.lua:1080: in function <data/npc/lib/npcsystem/modules.lua:1080>

 

[Itutorial]

Data/npc/lib/npcsystem/modules.lua
Go to line 1017

Do an if statement to check before that line:

if not items[itemid] then
    print(“Player “..Player(cid):getName().. “ tried to sell an invalid item”)
return false
end