How do i fix my bullet hole script thats doesn't work for some reason?

i recently made a fps game but the bullet hole thing doesn't work. it comes with a error that says Players.IEntity_303I.Backpack.LocalScript:22: attempt to perform arithmetic (add) on nil - heres the script :

local cam = workspace.Camera
local Mouse = game.Players.LocalPlayer:GetMouse()
local Hand = game.Players.LocalPlayer.CharacterAdded:Wait():WaitForChild("Right Arm"):Clone()
local Model = Instance.new("Model")

Model.Name = game.Players.LocalPlayer.Name.."'s Model"
Model.Parent = workspace
Hand.Parent = Model
Hand.Name = "RightArm1"
game:GetService("RunService").RenderStepped:Connect(function()
	for i = 0,1,.0001 do
		wait()
		Hand.CFrame = Hand.CFrame:Lerp(cam.CFrame * CFrame.new(1,-1,-2), i)
	end
end)
Mouse.Button1Down:Connect(function()
	local Decalpart = Instance.new("Part")
	local hit,pos,normal = workspace:Raycast(Hand.Position,Hand.CFrame.LookVector)
	Decalpart.Transparency = 1
	Decalpart.Size = Vector3.new(1,1,1)
	Decalpart.Parent = workspace
	Decalpart.CFrame = CFrame.new(pos,pos + normal)
	local decal = "rbxassetid://73737626"
	decal.Parent = Decalpart
	decal.Face = "Front"
end)