Here the script where the error is :
local player = game.Players.LocalPlayer
script.Parent.MouseButton1Click:Connect(function(click)
if player.leaderstats.Money.Value >= 10 then
player.leaderstats.Money.Value = player.leaderstats.Money.Value - 10
game.ReplicatedStorage.Tools.BlueWeigth = player:WaitForChild("Backpack")
end
end)
The error line is the 7 and the error is : 18:16:50.618 - BlueWeigth is not a valid member of Folder

2 comments
Your trying to access a child if tool that doesnt exist
It do