How do I fix error: attempt to index nil with 'WaitForChild'?

-- Define variables

local Replicated = game:GetService("ReplicatedStorage")

local ServerStorage = game:GetService("ServerStorage")

local MapsFolder = ServerStorage:WaitForChild("Maps")
 
local Status = ReplicatedStorage:WaitForChild("Status")

local GameLength = 500

local reward = 50

-- Game loop

while true do
	
end

	Status.Value = "Waiting for enough players"	
	
	repeat wait(1) until game.Players.NumPlayers >= 2
	
	Status.Value = "Intermission"
	
    wait(10)

    local plrs = {}

    for i, player in pairs(game.Players:GetPlayers()) do
		if player then
			table.insert(plrs,player) -- Add each player into plrs table
		end
	end
	
	wait(2)
	
	local AvailableMaps = MapsFolder:GetChildren()

	local ChosenMap =AvailableMaps[math.random(1,#AvailableMaps)]
	
	Status.Value = ChosenMap.Name.." Chosen"
	
	local ClonedMap = ChosenMap:Clone()
	CloneMap.Parent = workspace