Script that implemented this callback has been destroyed?

I was testing my game out and i found this error in the output. It broke a script of mine. What's wrong?

Script 1:

local timeToChange = script.Parent.timeToChange
local timeToChangeNoob = script.Parent.timeToChangeNoob
local timeToChangeGuest = script.Parent.timeToChangeGuest
local Deactivated = script.Parent.Deactivated
local RepStore = game:GetService("ReplicatedStorage")

function ManageGUIs()
    for _, p in pairs (game.Players:GetChildren()) do
        if p.Character ~= nil and p.Character.Humanoid ~= nil and p.Character.Humanoid.Health>0 and p.Character:findFirstChild("Torso") then
            local torso = p.Character.Torso
            if (torso.Position - script.Parent.Position).magnitude < 20 then
                --Open Gui
                RepStore.OpenCloseGUI:InvokeClient(p,script.Parent,true)
                --Set GUI Spawn Team Color
                RepStore.ModificateGUI:InvokeClient(p,"SpawnTeamColor",script.Parent.BrickColor.Color)
                if not Deactivated.Value then
                    RepStore.ModificateGUI:InvokeClient(p,"Time",10-timeToChange.Value)
                    RepStore.ModificateGUI:InvokeClient(p,"ProgressBarColor",script.Parent.BrickColor.Color)
                else
                    if timeToChangeNoob.Value>timeToChangeGuest.Value then
                        RepStore.ModificateGUI:InvokeClient(p,"ProgressBarColor",Color3.new(1,1,0))
                        RepStore.ModificateGUI:InvokeClient(p,"Time",timeToChangeNoob.Value)
                    else
                        RepStore.ModificateGUI:InvokeClient(p,"ProgressBarColor",Color3.new(0,0,0))
                        RepStore.ModificateGUI:InvokeClient(p,"Time",timeToChangeGuest.Value)
                    end

                end
            elseif RepStore.ModificateGUI:InvokeClient(p,"CheckSpawn") == script.Parent then -- >>ERROR<<
                RepStore.OpenCloseGUI:InvokeClient(p,nil,false)
            end
        else
            RepStore.OpenCloseGUI:InvokeClient(p,nil,false)
        end
    end
end

while wait(0) do
    ManageGUIs()
end

Script 2 (The one that receives the InvokeClient(p,"CheckSpawn"))

wait(1)
local RepStore = game:GetService("ReplicatedStorage")
local spawnTeamColor = script.Parent.Frame.SpawnLocationImage.TeamColor
local Time = script.Parent.Frame.UnderProgressBar.ProgressBar.LocalScript.Time
local ProgressBar = script.Parent.Frame.UnderProgressBar.ProgressBar
local Spawn = script.SpawnPoint

function OpenGUI(spawn,canOpen)
    if canOpen and Spawn.Value ~= nil then
        script.Parent.Frame:TweenPosition(UDim2.new(1,-220,1,-70),"Out","Bounce",0.5,true)
    else
        script.Parent.Frame:TweenPosition(UDim2.new(1,80,1,-70),"Out","Bounce",0.5,true)
    end
end

function ModificateGUI(WTM, value1)
    if WTM == "SpawnTeamColor" then
        if value1 == BrickColor.new("New Yeller").Color then
            spawnTeamColor.BackgroundColor3 = value1
            spawnTeamColor.BorderColor3 = Color3.new(1,0.67,0)
            script.Parent.Frame.BackgroundColor3 = Color3.new(1,0.67,0)
        elseif value1 == BrickColor.new("Mid gray").Color then
            spawnTeamColor.BackgroundColor3 = value1
            spawnTeamColor.BorderColor3 = Color3.new(0.5,0.5,0.5)
            script.Parent.Frame.BackgroundColor3 = Color3.new(0.5,0.5,0.5)
        elseif value1 == BrickColor.new("Really black").Color then
            spawnTeamColor.BackgroundColor3 = value1
            spawnTeamColor.BorderColor3 = Color3.new(0.25,0.25,0.25)
            script.Parent.Frame.BackgroundColor3 = Color3.new(0.25,0.25,0.25)
        end
    elseif WTM == "Time" then
        Time.Value = value1
    elseif WTM == "ProgressBarColor" then
        ProgressBar.BackgroundColor3 = value1
    elseif WTM == "CheckSpawn" then
        return Spawn.Value
    end
end

RepStore.OpenCloseGUI.OnClientInvoke = function(spawn,canOpen)
    Spawn.Value = spawn
    OpenGUI(spawn,canOpen)
end

RepStore.ModificateGUI.OnClientInvoke = function(whatToModificate,value1)
    local fun = ModificateGUI(whatToModificate,value1)
    if fun ~= nil then
        return fun
    end
end