Trying to make a follow script that applies to NPC's around the player?

game.Players.PlayerAdded:connect(function(Player)
local p = game.Workspace:WaitForChild(Player.Name)
print (p)
local f = p.UpperTorso.Position
print (f)
local dist = 15
local pos1 = f
		for i,v in pairs(game.Workspace.CrystalMobA.UndeadWarrior:GetChildren())do
		 if v.Name == "HumanoidRootPart" then
			print (v)
			local z = v.Parent.Humanoid
			local pos2 = v.Position
		    local magnitude = (pos1 - pos2).magnitude
		    if magnitude <=15 and z then
			if p.Humanoid ~= nil then 
				print('humanoid')
				while true do
	wait(1)
	local target = f(v.Position)
	if target ~= nil then
		print ("Following")
		v.Parent.Humanoid:MoveTo(target.Position, target)
						end
					end
				end
			end
		end
	end
end)