AI walking off the earth?

So basically I'm trying to make a simple AI that has priorities

Priorities 1- Light 2- Sound 3- Humans

But for some reason the AI just walks off the earth and ignores them all Here's my script:

local NPC = script.Parent
local Humanoid = NPC:WaitForChild("Humanoid")
local Rootpart = NPC:WaitForChild("HumanoidRootPart")
local DetectionDistance = 50

local GOTO = nil
local Object = nil

UpdateAI = coroutine.create(function()
	
	while wait(0.025) do
		
		------------
		
		if GOTO == nil then
			GOTO = Rootpart
		end
		
		------------
		
		if Object == nil or GOTO == nil then
			Object = nil
			GOTO = Rootpart
		end
		
		------------
		
		if GOTO and Object then
			local CheckDistance = DetectionDistance
			
			if Object:IsA("Sound") and Object.Volume >= 5 then
				CheckDistance = DetectionDistance * 2
			end
			
			if (Rootpart.Position - GOTO.Position).Magnitude > CheckDistance then
				Object = nil
				GOTO = nil
			end
		end
		
		------------
		
		if GOTO then
			Humanoid:Move(GOTO.Position)
		end
		
		------------
		
		for i,e in pairs(workspace:GetDescendants()) do
			------------------------
			--Lights
			if e:IsA("Light") and e.Parent:IsA("BasePart") and e.Enabled == true then
				if (Rootpart.Position - e.Parent.Position).Magnitude <= DetectionDistance then
					Object = e
					GOTO = e.Parent
				end
			--Sounds
			elseif e:IsA("Sound") and e.Parent:IsA("BasePart") and e.Playing == true then
				local CheckDistance = DetectionDistance
				
				if e.Volume >= 5 then
					CheckDistance = DetectionDistance * 2
				end
				
				if (Rootpart.Position - e.Parent.Position).Magnitude <= CheckDistance then
					if Object:IsA("Light") then
						return
					end
					Object = e
					GOTO = e.Parent
				end
			--Humans
			elseif e:IsA("Model") and e:FindFirstChild("HumanoidRootPart") and e.PrimaryPart then
				if Object == nil then
					if (Rootpart.Position - e.PrimaryPart.Position).Magnitude <= DetectionDistance then
						Object = e
						GOTO = e.PrimaryPart
					end
				end
			end
			------------------------
		end
		
		------------
		
	end
	
end)

coroutine.resume(UpdateAI)

1. It's not a good idea to use:

workspace:GetDescendants()

Why? Because :GetDescendants() iterates through every instance in the workspace. Imagine having hundreds of thousands of instances in the workspace and iterating through all of that? It will take a long time, and the response won't be fast. That's why it's better you use CollectionService for your Lights.

1. Your if statements are messy. Too many ifs could make your code confusing not just for other people but for you as well! You're also changing the values GOTO and Object so many times; can't figure out why or what's really going on.

2. I can't really give you a code that works since I'm having a hard time reading it. But try minimizing those methods.

3. For my final suggestion, change Humanoid:Move(GOTO.Position) to Humanoid:MoveTo(GOTO.Position) in line 44.