What does attempt to index field '?' (a nil value) mean?

Here is the full code

--[[{Tables}]]

local reaped = {} 
local tributes = {}
local tributesDead = {}
local tributesAlive = {}
SortedTributes = {{},{},{},{},{},{},{},{},{},{},{},{},{}}

-----------------------------------------------------

--[[{Variables}]]

local previousVictor = "No One!"
local arenaBiome = "???"
local stage = "???"
local num = game.Players.NumPlayers
local min_players = 2
local asset = "http://roblox.com/asset/?id="
localbadge = game:GetService("BadgeService")
local year = 1
local center = CFrame.new(0, 6.99, 0) 

----------------------------------------------------

--[[{Leaderstats}]]

game.Players.PlayerAdded:connect(function(plr)
    local gui = game.ReplicatedStorage.Announce:Clone(); gui.Parent = plr.PlayerGui
    local ov = Instance.new("ObjectValue", plr); ov.Name = "leaderstats"
    local wins = Instance.new("NumberValue", ov); wins.Name = "Wins"
    local nv =Instance.new("NumberValue",ov); nv.Value = 0; nv.Name="SP"
end)

---------------------------------------------------

--[[{Side functions}]]

function Cannon()
        script.Cannon:Play()
end

function Anthem()
        game.Workspace.PanemAnthem:Play()
end

function Updates()
    local updates = game.Workspace.Lobby:FindFirstChild("Updates")
    --[[Properties]]--
    --Velocity edits
    updates.BodyAngularVelocity.angularvelocity = Vector3.new(0, 1, 0)
    updates.BodyAngularVelocity.maxTorque = Vector3.new(4000, 4000, 4000)
    updates.BodyAngularVelocity.P = 1250
    --Position edits
    updates.BodyPosition.D = 1250
    updates.BodyPosition.maxForce = Vector3.new(400000, 400000, 400000)
    updates.BodyPosition.P = 10000
    updates.BodyPosition.position = Vector3.new(5.833, 458.752, 7.948)
    --[[Printing]]--
    print("The Update's position is Good!")
end

function CreatePeds()
        local peds = Instance.new("Model", game.Workspace); peds.Name = "Pedestals"
        for i = 1,24,1 do
                local p = Instance.new("Part", peds)
                p.Anchored = true
                p.Locked = true
                p.Size = Vector3.new(6,1,6)
                p.BrickColor = BrickColor.new("Mid gray")
                p.Name = ("Ped"..i)
                p.TopSurface = "SmoothNoOutlines"
                p.BottomSurface = "SmoothNoOutlines"
                p.CFrame = center*CFrame.Angles(0, i/24*math.pi, 0)*CFrame.new(-115, -0.8, 0)
                Instance.new("CylinderMesh", p)
                local pa = p:Clone()
                pa.Parent = p
                pa.Locked = true
                pa.Name = "PedPart"
                pa.TopSurface = "SmoothNoOutlines"
                pa.BottomSurface = "SmoothNoOutlines"
                pa.Size = Vector3.new(5,2,5)
                pa.CFrame = center*CFrame.Angles(0, i/24*math.pi, 0)*CFrame.new(-115, -1, 0)
                pa.BrickColor=BrickColor.new("Dark stone grey")
                wait(0.1)
        end
end

function announce(text)
    game.Workspace.Announcement.Value = text
    print("Announcement: "..text)
end
------------------------------------------------------------------

--{[[Main game functions]]}

Updates()
CreatePeds()

--[[Announcing]]

while wait() do
        if game.Players.NumPlayers < 2 then 
            announce("Need 1 More Player to Start!")
            wait(3)
            announce("Invite Some Friends!")
            wait(3)

            --Specifying years

        elseif game.Players.NumPlayers >= 2 then
                game.Workspace.GameStatus.Value = "Reaping"
                local lastdig = tostring(year):sub(tostring(year):len())
                if lastdig == "1" then 
                    year = (tostring(year).."st")
                elseif lastdig == "2" then 
                    year = (tostring(year).."nd")
                elseif lastdig == "3" then 
                    year = (tostring(year).."rd")
                elseif lastdig >= "4" or lastdig == "0" then 
                    year = (year.."th")
                end

                --Anouncing

                announce("Welcome to the "..year.." Annual Hunger Games!")
                wait(3)
                announce("And May the odds be ever in your Favor!")
                wait(3)
                announce("Tributes are being Reaped...")
                wait(3)
                announce("")

                break
        end
end

--[[Waiting]]
repeat wait() until game.Workspace.Announcement.Value == ""

--[[Reaping]]

game.Workspace.Start.Value = true

if game.Workspace.Start.Value == true then
    print("Starting the "..year.." Annual Hunger Games!")

    --Main reaping

    if game.Players.NumPlayers > 24 then
        for i = 1,24 do
            local plrs = game.Players:GetPlayers()
            local ranPlayer = (plrs[math.random(1,#plrs)])
            for a,b in pairs(tributes) do
                if b.Name ~= ranPlayer.Name then
                    table.insert(tributes,ranPlayer)
                else
                    repeat
                        ranPlayer = plrs[math.random(1,#plrs)]
                    until 
                        ranPlayer.Name ~= b.Name
                    table.insert(tributes,ranPlayer)
                end
            end
        end
    else
        for a,b in pairs(game.Players:GetPlayers()) do
            table.insert(tributes,b)
        end
    end

    --Inserting values

    for i,v in pairs(tributes) do
        stat = Instance.new("StringValue", v); stat.Value = "Tribute"
    end

    --Grouping tributes

    local currentTab = 1
    local seminum = 0

    for i,v in pairs(tributes) do
        seminum = seminum + 1
        if seminum == 3 then
            seminum = 0
            currentTab = currentTab + 1
        end
        table.insert(SortedTributes[currentTab],v)
    end

    --Announcing tributes

    for i,v in pairs(SortedTributes) do
        announce("District "..i..": "..v[1].Name..", and "..v[2].Name.."!")
        wait(1)
    end

    --Teleporting tributes

Anthem()

    for i,v in pairs(tributes) do
        v.Character.Torso.CFrame = CFrame.new(game.Workspace.Pedestals:FindFirstChild("Ped"..i).Position + Vector3.new(0,3,0))
    end
end