It saids backpack is not a valid member of model do i use waitforchild or what do i do?

around line 55 it errors

local player = game.Players.LocalPlayer
local character = player.Character
local items = {}
local buttons = {}
game.StarterGui:SetCoreGuiEnabled(Enum.CoreGuiType.Backpack,false) --sets this to false I already knew that lmao

function search(location)
    for i,v in pairs(location:GetChildren()) do -- Find all the children
        if v:isA('Tool') then -- If V is a Tool while looping
            table.insert(items,v) -- insert all tools


        end
    end
end

function refresh()
    for i,v in pairs(buttons) do 
        v:Destroy()

    end
    for i,v in pairs(items) do
        local button = script.Sample:Clone()
        button.Name = v.Name
        button.LayoutOrder = i
        button.Parent = script.Parent.Handler
        button.Image = v.TextureId
        table.insert(buttons,button)
        button.MouseButton1Click:Connect(function()
            if script.Parent.Handler.Selected.Value == nil or script.Parent.Handler.Selected.Value ~= v then
                script.Parent.ItemName.Text = v.Name -- sets v Name
                script.Parent.ItemImage.Image = v.TextureId --sets image to text image
                if script.Parent.Handler.Selected.Value ~= script.Parent.Handler.Equip.Value then
                    script.Parent.Handler.Location.Value = v.Parent
                    script.Parent.Equip.Text = "Equip"
                elseif script.Parent.Handler.Selected.Value == script.Parent.Handler.Equip.Value then
                    script.Parent.Handler.Location.Value = v.Parent
                    script.Parent.Equip.Text = "Unequip"

                end
            end
        end)
    end
    end

    function backpackRefresh()
        items = {}
        search(character)
        search(player.Backpack)
        refresh()

    end

    backpackRefresh()
player.Backpack .ChildAdded:Connect(backpackRefresh)
player.Backpack.ChildRemoved:Connect(backpackRefresh)

                                    -- I assume error is somewhere here 

character.Backpack.ChildAdded:Connect(backpackRefresh)

character.Backpack.ChildRemoved:Connect(backpackRefresh)

it keeps giving me error