attempt to index field '?' (a nil value) help?

How can i fix this -> 03:48:12.854 - Workspace.marobskoco.Helper.AI.Pathfinding:50: attempt to index field '?' (a nil value)

wait(2)

local PathfindingService = game:GetService("PathfindingService")
	 
-- Variables for the zombie, its humanoid, and destination
local zombie = script.Parent.Parent
local humanoid = zombie:WaitForChild("Humanoid")
local destination = script.Parent.Parent.Parent
local olddestination

local path = PathfindingService:CreatePath()
	
local waypoints
local currentWaypointIndex

	
local function NewPath(Path)
		
	olddestination = destination.Head.Position
		
	path:ComputeAsync(zombie.HumanoidRootPart.Position, Path.PrimaryPart.Position)
	-- Empty waypoints table after each new path computation
	waypoints = {}
 	
	waypoints = path:GetWaypoints()
	
	-- Move to first waypoint
	currentWaypointIndex = 1
	
	
end

NewPath(destination)
	
while true do
	
	local zombiehead = zombie.Head.Position
	local master = destination.Head.Position
	local distance = (master - zombiehead).magnitude
	local hm = destination.Humanoid
	local max_distance = 7
	local lift1 = game.Workspace.Lifts.Lift1.Lift.Position
	local lift2 = game.Workspace.Lifts.Lift2.Lift.Position
	
	if distance > max_distance then
		
		
		if waypoints then
			
			if waypoints == nil or currentWaypointIndex == nil or waypoints[currentWaypointIndex].Position == nil or waypoints[currentWaypointIndex] == nil or hm.Jump == true then
				NewPath(destination)
			end
			
			local one = (lift1 - master).magnitude
			local two = (lift2 - master).magnitude
			local max = 35

			if one and two > max then
				
				humanoid:MoveTo(waypoints[currentWaypointIndex].Position)
				
				if humanoid.MoveToFinished:wait() then
					currentWaypointIndex = currentWaypointIndex + 1
--				humanoid.MoveToFinished:wait()
				else 
					humanoid.Jump = true
					NewPath(destination)
				end
				adistance = (master - olddestination).magnitude
		
				if adistance > 3 then
					NewPath(destination)
				end
				
			end
	
		end
		
		
	end
	
	wait()
end