got some problems with container widget

[5Y2h6YCa]

Firstly i wrote this in modmain.lua

local params = {}

params.yuzu_ammo =

{

    widget =

    {

        slotpos =

        {

            Vector3(0,   32 + 4,  0),

        },

        slotbg =

        {

            { image = "slingshot_ammo_slot.tex" },

        },

        animbank = "ui_cookpot_1x2",

        animbuild = "ui_cookpot_1x2",

        pos = Vector3(0, 15, 0),

    },

    usespecificslotsforitems = true,

    type = "hand_inv",

    excludefromcrafting = true,

}

 

local containers = require "containers"

 

local old_widgetsetup = containers.widgetsetup

 

function containers.widgetsetup(container, prefab, data)

    local pref = prefab or container.inst.prefab

    if pref == "yuzu_ammo" then

        local t = params[pref]

        if t ~= nil then

            for k, v in pairs(t) do

                container[k] = v

            end

            container:SetNumSlots(container.widget.slotpos ~= nil and #container.widget.slotpos or 0)

        end

    else

        return old_widgetsetup(container, prefab, data)

    end

end

Then i added this in the prefab functions

inst.components.container:WidgetSetup("yuzu_ammo")

At frist it worked,but the problem showed up after i add caves to my world.

The report shows:

"scripts/widgets/containerwidget.lua":30: attempt to index local "widget"(a nil value)