Does anyone know how to help me with this issue im having with my NPC follow player script?

So im working on a game and im trying to get an NPC to follow a player around the map. So far i have this script going.

local NPC = game.Workspace.Matt
local pathfinding_service = game:GetService("PathfindingService")

function getClosestPlayer()
	local closest_player, closest_distance = nil, 200
	for i, player in pairs(workspace:GetChildren()) do
		if player:FindFirstChild("Humanoid") and player ~= NPC then
			local distance = (NPC.PrimaryPart.Position - player.PrimaryPart.Position).Magnitude
			if distance < closest_distance then
				closest_player = player
				closest_distance = distance
			end
		end
	end
	return	closest_player, closest_distance
end

while true do
	local path = pathfinding_service:CreatePath()
	local player, distance = getClosestPlayer()
	if player and distance > 10 then
		path:ComputeAsync(NPC.HumanoidRootPart.Position, player.PrimaryPart.Position)
		local waypoints = path:GetWaypoints()
		for _, waypoint in pairs(waypoints) do
			NPC.Humanoid.MoveTo(Waypoint.Position)
			while true do
				local distance = (NPC.PrimaryPart.Position - waypoint.Position).Magnitude
				local distance_from_player = (NPC.PrimaryPart.Position - player.PrimaryPart.Position).Magnitude
				if distance < 5 then
					break
				end
				if distance_from_player < 10 then
					NPC.Humanoid:MoveTo((NPC.HumanoidRootPart.CFrame*CFrame.new(0,0,-3)).p)
					break
				end
				wait()				
		     end
	     end
    end
	wait()
end
	

It is giving me this in the output

Workspace.Matt.Follow the Player:8: attempt to index nil with 'Position'

this is the line it is referencing

local distance = (NPC.PrimaryPart.Position - player.PrimaryPart.Position).Magnitude

If anyone has any idea how to fix this issue, let me know please! thanks!

Here is a better way to get the closest player:

local closestM = math.huge --To make sure every number is less than this
local closestP = nil

for i,v in pairs(game.Players:GetPlayers()) do
	local mag = (NPC.HumanoidRootPart.Position - v.Character.HumanoidRootPart.Position).magnitude
	if mag < closestM then
		closestM = mag
		closestP = v
	end
end
--you can use the closestP as you want

I replaced the getClosestPlayer function with mine and every PrimaryPart with HumanoidRootPart. So now your script should look like this:

local NPC = game.Workspace.Matt
local pathfinding_service = game:GetService("PathfindingService")
function getClosestPlayer()
	local closest_distance = math.huge
	local closest_player = nil

	for i,v in pairs(game.Players:GetPlayers()) do
		local mag = (NPC.HumanoidRootPart.Position - v.Character.HumanoidRootPart.Position).magnitude
		if mag < closest_distance then
			closest_distance = mag
			closest_player = v
		end
	end
	return  closest_player, closest_distance
end

while true do
	local path = pathfinding_service:CreatePath()
	local player, distance = getClosestPlayer()
	local player_char = player.Character
	if player and distance > 10 then
		path:ComputeAsync(NPC.HumanoidRootPart.Position, player_char.HumanoidRootPart.Position)
		local waypoints = path:GetWaypoints()
		for _, waypoint in pairs(waypoints) do
			NPC.Humanoid.MoveTo(waypoint.Position)
			while true do
				local distance = (NPC.HumanoidRootPart.Position - waypoint.Position).Magnitude
				local distance_from_player = (NPC.HumanoidRootPart.Position - player_char.HumanoidRootPart.Position).Magnitude
				if distance < 5 then
					break
				end
				if distance_from_player < 10 then
					NPC.Humanoid:MoveTo((NPC.HumanoidRootPart.CFrame*CFrame.new(0,0,-3)).p)
					break
				end
				wait()              
			end
		end
	end
	wait()
end

##Problem

The reason it didn't work was because there was no HumanoidRootPart, hence the error.

Check by clicking on this hyperlink

Make sure your NPC has a HumanoidRootPart by checking.

Fixed Script:

local NPC = game.Workspace.Matt
local pathfinding_service = game:GetService("PathfindingService")

function getClosestPlayer()
	local closest_player, closest_distance = nil, 200
	for i, player in pairs(workspace:GetChildren()) do
		if player:FindFirstChild("Humanoid") and player ~= NPC then
			local distance = (NPC.PrimaryPart.Position - player.PrimaryPart.Position).Magnitude
			if distance < closest_distance then
				closest_player = player
				closest_distance = distance
			end
		end
	end
	return  closest_player, closest_distance
end

while true do
	local path = pathfinding_service:CreatePath()
	local player, distance = getClosestPlayer()
	if player and distance > 10 then
		path:ComputeAsync(NPC.HumanoidRootPart.Position, player.PrimaryPart.Position)
		local waypoints = path:GetWaypoints()
		for _, waypoint in pairs(waypoints) do
			NPC.Humanoid:MoveTo(waypoint.Position)
			while true do
				local distance = (NPC.PrimaryPart.Position - waypoint.Position).Magnitude
				local distance_from_player = (NPC.PrimaryPart.Position - player.PrimaryPart.Position).Magnitude
				if distance < 5 then
					break
				end
				if distance_from_player < 10 then
					NPC.Humanoid:MoveTo((NPC.HumanoidRootPart.CFrame*CFrame.new(0,0,-3)).p)
					break
				end
				wait()              
			end
		end
	end
	wait()
end

Recommendation(s):

• Use :MoveTo because .MoveTo isn't a function.

Also, ensure that your script is in Workspace.

Thanks, JesseSong