How to fix this error, Didn't had it until restarted?

Hi, so i got this error and idk what the hell is going on since i never had this error

error: ServerScriptService.leaderstats:84: attempt to index nil with 'UserId'

game:BindToClose(function(player)
	for _, Player in pairs(game.Players:GetPlayers()) do
		local playerUserId = "player_"..player.UserId