"Workspace.Part.Script:10: attempt to index nil with 'HumanoidRootPart'"?

local debounce = false
local part = script.Parent
local interval = 4
part.Touched:Connect(function(hit)
    if debounce == false then
        debounce = true
        if hit and hit.Parent and hit.Parent:FindFirstChild("Humanoid") then
            local PoisonPart = Instance.new("Part") 
            PoisonPart.Parent = hit.Parent
            PoisonPart.Position = CFrame.Parent.HumanoidRootPart.Position
            PoisonPart.Name = ("PoisonPart")
            local weld = Instance.new("Weld")
            weld.Part0 = ("PoisonPart")
            weld.Part1 = ("HumanoidRootPart")
            weld.Parent = PoisonPart
        end
        wait(interval)
        debounce = false
    end
end) 

i'm trying to make a script that creates a part inside you but for some reason i get an error named "Workspace.Part.Script:10: attempt to index nil with 'HumanoidRootPart'" leading to the part being located at the spawn how do i fix this?