Why is the "player" returning as nil?

local pf = Instance.new("Folder");
pf.Name = "PlayerFolder";
pf.Parent = workspace;
local parentorso = script.Parent.Torso;
local h = script.Parent.Humanoid;
local dist = 20
local function sortplayers(player)
	player.CharacterAdded:Connect(function(character)
		character.Parent = pf;
	end)
end

local follow

local function GetNearestPlayer(WorldPos)
	for _,player in pairs(pf:GetChildren()) do
		if player.HumanoidRootPart then
			if player.Humanoid.Health > 0 then
				local distance = (player.HumanoidRootPart.Position - WorldPos).Magnitude
				if distance >= 20 then
					dist = distance
					follow = workspace[player].Torso
					print(player.Name)
					return player;
				end
			end
		end
	end
end

while true do
	wait(1)
	GetNearestPlayer()
	print(follow.Parent.Name)
end

game.Players.PlayerAdded:Connect(sortplayers)


local pfs = game:GetService("PathfindingService");
local path = pfs:FindPathAsync(parentorso,follow);
local points = path:GetWaypoints();
if path.Status == Enum.PathStatus.Success then
	for i,v in pairs(points) do
		h:MoveTo(v.Position)
		h.MoveToFinished:Wait()
		if v.Action == Enum.PathWaypointAction.Jump then
			h.Jump = true
		end
	end
end

I am trying to make a script that makes a NPC walk towards the nearest player. Unfortunately, the player keeps returning as nil?