Data Store Replicated error?

I already know that parts and things such as that cannot be saved in a DataStore! * I am new (Today new) at Data Stores so I'll probably have "newb" mistakes.* I am basically testing DataStores to see if I know how to even do them yet I'm getting and error. I have 3 scripts, 1 that will save data when you leave, one that uses the data when you join(if any) and the last one that uses OnClose so I can keep the server open when it's suppose to shutdown for Data Saving.

Here's the Added script:

game.Players.PlayerAdded:connect(function(plr)
    local DS = game:GetService("DataStoreService"):GetDataStore(plr.Name)
    game.Players:WaitForChild("leaderstats"):WaitForChild("Stage")
    if DS:GetAsync(plr.Name) ~= 0 then
        plr.leaderstats.Stage.Value = DS:GetAsync(plr.Name)
    else
        print(plr.Name.."Doesn't Need Data Transfer")   
    end
end)

Here's the Leaving script:

game.Players.PlayerRemoving:connect(function(plr)
    local DS = game:GetService("DataStoreService"):GetDataStore(plr.Name)
    local Key = plr.Name
    if plr.leaderstats.Value == 0 then
        print("Ignore Data Save For "..plr.Name)
    elseif plr.leaderstats.Value >= 1 then
        DS:SetAsync(Key, plr.leaderstats.Stage.Value)
    end
end)

Here's the OnClose script:

game.OnClose = function()
    wait(3)
end

Please don't shy from sharing information so I may better myself in Data Stores.