Sometimes my script works and sometimes it wont. Has to do with FireClient, how do I fix this?

local opener = game.Workspace.OpenShop.Opener

local debounce = false


opener.Touched:Connect(function(hit)
	if not debounce then
		debounce = true
		
		local player = game.Players:GetPlayerFromCharacter(hit.Parent)

game.ReplicatedStorage.ShowGui2:FireClient(player)
		
		wait(4)
		debounce = false
	
	end
end)

I'm a little more new to scripting. Sometimes it will say error on line 12 which is the FireClient line. But sometimes it wont say that and my script will work.