My zombies aren't being destroyed once reaching the end part?

In my tower defense game, there are waypoints in a folder, which zombies have to travel to.

Once they reach the last waypoint in the folder, they are normally supposed to be destroyed. However, it gives me the error "42 is not a valid member of Folder "Workspace.Grassy.waypoints".

local PhysicsService = game:GetService("PhysicsService")
local ServerStorage = game:GetService("ServerStorage")
local mob = {}

function mob.Move(mob, map)
	local humanoid = mob:WaitForChild("Humanoid")
	local waypoints = game.Workspace.Grassy.waypoints

	for waypoint=3, #waypoints:GetChildren() do
		humanoid:MoveTo(waypoints[waypoint].Position)
		humanoid.MoveToFinished:Wait()
	    
	end
	
	mob:Destroy()
end

function mob.Spawn(name, quantity,  map)
	local mobExists = ServerStorage.Mobs:FindFirstChild(name)
	
	if mobExists then
		for i=1, quantity do
			task.wait(0.5)
			local newMob = mobExists:Clone()
			newMob.HumanoidRootPart.CFrame = map.Start.CFrame
			newMob.Parent = workspace.Mobs
			newMob.HumanoidRootPart:SetNetworkOwner(nil)
			
			for i, object in ipairs(newMob:GetDescendants()) do
				if object:IsA("BasePart") then
					PhysicsService:SetPartCollisionGroup(object, "Mob")
				end
			end
			
			newMob.Humanoid.Died:Connect(function()
				task.wait(0.03)
				newMob:Destroy()
			end)
			
			coroutine.wrap(mob.Move)(newMob, map)
		end
	else
		warn("rip")
	end
end

return mob

When the amount of waypoints are less than 30..It works again..However when I place back all the waypoints leading up to 41 it starts malfunctioning again. Any help?

In line 15, inside the parenthesis, why is there a "mob" inside when there's already a table named "mob", try changing it to function mob.Move(mobCharacter, map) maybe that's what causing the error.

for waypoint=3, #waypoints:GetChildren()-2 do

OR

for waypoint=1, #waypoints:GetChildren() do

Fixed code

function mob.Move(mob, map)
    local humanoid = mob:WaitForChild("Humanoid")
    local waypoints = workspace.Grassy.waypoints
    local waypoint = 3

   while waypoint <= #waypoints:GetChildren() do
        humanoid:MoveTo(waypoints[waypoint].Position)
        humanoid.MoveToFinished:Wait()
        waypoint += 1
   end

    mob:Destroy()
end

I don't think I have to explain this one.