GUI not getting inserted into playergui, how would I fix this?

local guiname = "PurchaseGUI"

script.Parent.Touched:connect(function(hit)
	if hit == nil then return end
	if hit.Parent == nil then return end
	
	local player = game.Players:GetPlayerFromCharacter(hit.Parent)
	if player ~= nil then
		if player:FindFirstChild("PlayerGui") then
			print("this is working")
			if not player.PlayerGui:FindFirstChild(guiname) then
				print("this is where the script stops working")
				local ui = script:FindFirstChild(guiname):clone()
				ui.Parent = player.PlayerGui
			end
		end
	end
end)

Hey all, thanks for reading! At

print("this is where the script stops working") 

The script stops working, who would have guessed ¯_(?)_/¯. I don't know why it stops but its probably a really obvious,

if not player.PlayerGui:FindFirstChild(guiname) then

That is the line that errors, Thanks!