Checking how many Players are in the Table?

So im trying to do a Queue thing. When you join the game there is a button called "PLAY" and i want that if u click it , it will add you to the _G.gameplayers {} table .

my Main script now should do the thing that it first checks before everything starts that atleast 1 player is in the _G.gameplayers {} table. If not it says " not enough Players ". My Error code is :

ServerScriptService.MAIN:14: attempt to compare number with nil

Here is my Click script where u need to click to be added to the table :

function join()
wait()
_G.gameplayers = {}
local human = game.Players:FindFirstChild("Humanoid")
if human then
    table.insert(_G.gameplayers, human.Name)
end
end 

script.Parent.MouseButton1Down:connect(join)

And here is the Main script where my Roundgame is

local replicatedstorage = game:GetService("ReplicatedStorage") 
local status = replicatedstorage:WaitForChild("InfoValue")
local mapstorage = game.workspace:WaitForChild("mapStorage")
RoundLive = false

--Falls jemand geld kriegt
--game.Players.leaderstats.Wins.Value = game.Players.leaderstats.Wins.Value + 1

while true do

_G.gameplayers = {}
if _G.gameplayers.NumPlayers == nil then
status.Value = "not enough players"
repeat wait(1) until _G.gameplayers.NumPlayers >- 2
end
end
wait(1)
for i = 10,0,-1 do
    status.Value = "Preparing game in "..i
    wait(1)
    if i == 0 then 
        status.Value = " "
    end
end

--_G.gameplayers = {}
--for i, v in pairs(game.Players:GetPlayers()) do
--if v then
--  table.insert(_G.gameplayers, v.Name)
--end
--end 
status.Value = "A new game is starting now."
wait(2)
status.Value = "Get ready to play!"
wait(3)

--Die Map wird in Workspace reinkopiert

local mapsinserverstorage = game:GetService("ServerStorage").Maps:GetChildren()
local chosenmap = mapsinserverstorage[math.random(1,#mapsinserverstorage)]
chosenmap:Clone().Parent = mapstorage
local spawns = chosenmap:WaitForChild("Spawns"):GetChildren()
for _,Player in pairs(game.Players:GetPlayers(_G.gameplayers)) do
    if Player and #spawns > 0 then
        local torso = Player.Character:WaitForChild("Torso")
        local allspawns = math.random(1, #spawns)
        local randomspawn = spawns[allspawns]
        if randomspawn and torso then
            table.remove(spawns, allspawns)
            --Teleportiere die Spieler in das Spiel

            torso.CFrame = CFrame.new(randomspawn.Position + Vector3.new(0,2,0))
            --Teleportiere den Gegner AI in die Map

            local enemie = game.ReplicatedStorage:FindFirstChild("Enemies"):GetChildren()
            GegnerStorage = game.workspace:WaitForChild("GegnerStorage")
            for _,obj in pairs(enemie) do
            obj:Clone().Parent = GegnerStorage
            end



            --Waffen werden hinzugefügt

            --local M4AR = game.ReplicatedStorage.M4AR
            --local newM4 = M4AR:Clone()
            --newM4.Parent = Player.Backpack
        end
    end
end

for i = 60,0,-1 do
    wait(1)
    --Wenn die Zeit abgelaufen ist
    if i == 0 then
        status.Value = "You Lost there was no Time left!"
        wait(2)
        break
    end
    --Die Gegner haben gewonnen da keine Spieler mehr am Leben sind
    if #_G.gameplayers == 0 then
                status.Value = "You Lost"
                wait(2)
                break
    end
    if #GegnerStorage:GetChildren() == 0 then
        status.Value = "You Won"
        wait(2)
        break
    else
        status.Value = i.." seconds remaining"
end
end

local spawns = game.Workspace.Lobby:WaitForChild("Spawns"):GetChildren()
for _,Player in pairs(game.Players:GetPlayers()) do
    if Player and #spawns > 0 then
        local torso = Player.Character:WaitForChild("Torso")
        local allspawns = math.random(1, #spawns)
        local randomspawn = spawns[allspawns]
        if randomspawn and torso then
            table.remove(spawns, allspawns)
            torso.CFrame = CFrame.new(randomspawn.Position + Vector3.new(0,2,0))
            Player.Backpack:ClearAllChildren()
            status.Value = " "
        end
    end
end
--Entfernt alle Tools am ende jeder Runde
--leert die Map aus Mapstorage und die Gegnerstorage komplett
mapstorage:ClearAllChildren{}
GegnerStorage:ClearAllChildren{}

wait(5)
for v, Player in pairs(game.Players:GetPlayers()) do
    v.Backpack:ClearAllChildren()
    v.Health = 100
    wait()


end

please ignore my german langue there . it doesnt affect the script :)) Thanks guys