Tool is not valid of folder?

So i got an error I don't know why i want to make max inventory less than 1 tool but this is how it done https://gyazo.com/b45cff28aa8c40fc4a3a1ae46783c22a

The clickdetector script

local items = game.Workspace.Items
local db = false
script.Parent.ClickDetector.MouseClick:Connect(function(plr)
	if db == false then
		db = true
		local backpack = plr:WaitForChild("Backpack")
		local tool = items.Tool or backpack
		if tool then
			tool.Parent = backpack
		end
	end
	db = false
end)

And this is the inventory less than 1 tool script

backpack = game.Players.LocalPlayer:WaitForChild("Backpack")
backpack.ChildAdded:Connect(function(child)
	local childamount = #backpack:GetChildren()
	if childamount > 1 then
		for i,tool in pairs(backpack:GetChildren()) do
			if tool ~= child then
				tool.Parent = game.Workspace.Items
				tool.Handle.Position = child.Handle.Position
			end
		end
	end
end)