attempt to index upvalue 'targetTorso' (a nil value), how could I fix this [?]

I thank Kingdom for providing a great example.

#Objective:# My Objective is pretty simple, it's to create an NPC Respawn script that simply respawns the NPC to where it was from (place in studio) when it dies or falls out of the world. I'm trying to make scripts not laggy and avoid loops as much as possible.

#Set-up:# in workspace I have a Folder called Bandits which holds all the NPC's. in ServerStorage I have a Folder called NPCBackup Which holds a new Bandit ready to be used. in ServerScriptService I have a script that manages the NPC's. in ReplicatedStorage I have a Folder called ModuleScripts That holds ModuleScripts.

#Problem:# An error appears during testing but I'm not sure how to deal with it. When I try to make add an if statement, it just stops the entire system completely.

#Script:#

local RunService = game:GetService("RunService")
local Settings = require(game:GetService("ReplicatedStorage").ModuleScripts.SETTINGS)
local Respawn_Time = Settings.BANDIT.RESPAWN_TIME
local plrServ = game:GetService('Players')
local NPCBackup = game:GetService('ServerStorage').NPCBackup.Bandit

local function getClosestPlayer(myPos)
	local pos, tor = Settings.BANDIT.RANGE
	for _, plr in pairs(plrServ:GetPlayers()) do
		if plr.Character then
			if (plr.Character.PrimaryPart.Position - myPos).Magnitude < pos then
				pos = (plr.Character.PrimaryPart.Position - myPos).Magnitude
				tor = plr.Character.PrimaryPart
			end
		end
	end
	
	return tor
end

local function setupNPC(Bandit, BanditPosition)
	
	local hum = Bandit.Humanoid
	local npcPrimaryPart = Bandit.PrimaryPart
	local targetTorso
	spawn(function() 
		while wait(1) do
			targetTorso = getClosestPlayer(npcPrimaryPart.Position)
			hum:MoveTo(targetTorso.Position, targetTorso)
		end
	end)
	--hum:MoveTo(targetTorso.Position, targetTorso)
	
	-- clone new npc at same position
	hum.Died:Connect(function()
		wait(Settings.BANDIT.RESPAWN_TIME)
		local cln = NPCBackup:Clone()
		cln:SetPrimaryPartCFrame(BanditPosition)
		cln.Parent = workspace.Bandits
		Bandit:Destroy()
		setupNPC(cln, BanditPosition)
	end)
end

for _, Bandit in pairs(workspace.Bandits:GetChildren()) do
	spawn(function() setupNPC(Bandit, Bandit.PrimaryPart.CFrame) end)
end

This is the section where it errors:

	spawn(function() 
		while wait(1) do
			targetTorso = getClosestPlayer(npcPrimaryPart.Position)
			hum:MoveTo(targetTorso.Position, targetTorso)
		end
	end)

#Error:# 17:38:34.068 - ServerScriptService.NPCFollow.NPC Commander:29: attempt to index upvalue 'targetTorso' (a nil value) 17:38:34.069 - Stack Begin 17:38:34.069 - Script 'ServerScriptService.NPCFollow.NPC Commander', Line 29 17:38:34.070 - Stack End

I appreciate any feedback I get that improves this code to the best it can be or fixes my issue. Thanks for reading.