Not a valid member of something in workspace

Hey so i got this script

local ReplicatedStorage = game:GetService("ReplicatedStorage")
local EventsFolder = ReplicatedStorage:WaitForChild("Events")
local spawnTowerEvent = EventsFolder:WaitForChild("PlaceEvent")
local ServerStorage = game:GetService("ServerStorage")
local animateTowerEvent = EventsFolder:WaitForChild("AnimateTower")
local tower = {}

function FindNearestTarget(newTower, range)
	local maxDistance = 15
	local nearestTarget = nil

	for i, target in ipairs(workspace.Mobs:GetChildren()) do
		local distance = (target.HumanoidRootPart.Position - tower.HumanoidRootPart.Position).Magnitude
		if distance < range then
			nearestTarget = target
			range = distance
		end
	end

	return nearestTarget
end

function tower.Attack(newTower, player)
	local config = newTower.Config
	local target = FindNearestTarget(newTower, config.Range.Value)
	if target then
		target.Humanoid:TakeDamage(config.Damage.Value)
		
		if target.Humanoid.Health <= 0 then
			player.Gold.Value += target.Humanoid.MaxHealth
		end
		
		task.wait(config.Cooldown.Value)
		end

	
	tower.Attack(newTower, player)
end
function tower.Spawn(player, name, cframe)
	local TowerExists = ReplicatedStorage.Towers:FindFirstChild(name)

	if TowerExists then
		local newTower = TowerExists:Clone()
		newTower.HumanoidRootPart.CFrame = cframe
		newTower.Parent = workspace.Towers
		newTower.HumanoidRootPart:SetNetworkOwner(nil)
		
		for i, object in ipairs(newTower:GetDescendants()) do

			if object:IsA("BasePart") then

				object.CollisionGroup = "Tower"
			end
		end
		coroutine.wrap(tower.Attack)(newTower, player)
	else
		warn("bro what")
	end
end

spawnTowerEvent.OnServerEvent:Connect(tower.Spawn)

return tower

and when i playtest the game i get this error
ServerScriptService.Main.PlaceModuleScript:55: Mobs is not a valid member of Workspace “Workspace”

are mobs in workspace? (extra characters)

uhhh so there was a little problem that iw as refering to workspace instead of a folder but even after doing that i still get the error.

alright i did something and it got fixed but now i get attempt to index with position.

your getting closer (more characters)

Is this the error? Why the tower has a HumanoidRootPart?