Can someone help me with my weld script? The problem is that it breaks.

so when I hold my tool it works just fine with the weld script. But when buy the tool from the shop the weld breaks and it scatters everywhere. Plz help me.

my weld script:

local prev 
local parts = script.Parent:GetChildren() 

for i = 1,#parts do 
    if (parts[i].className == "Part" or parts[i].className == "UnionOperation") then 
        if (prev ~= nil)then 
            local weld = Instance.new("Weld") 
            weld.Part0 = prev 
            weld.Part1 = parts[i] 
            weld.C0 = prev.CFrame:inverse() 
            weld.C1 = parts[i].CFrame:inverse() 
            weld.Parent = prev 
        end 
        prev = parts[i] 
    end 
end

my shop script:

local player = game.Players.LocalPlayer

script.Parent.MouseButton1Down:Connect(function()
    if player.leaderstats.Cash.Value >= 60 then 
        player.leaderstats.Cash.Value = player.leaderstats.Cash.value - 10
        game.ReplicatedStorage.Weapons.SithSaber:Clone().Parent = player:WaitForChild("Backpack")
    end
end)