How can I prevent data from being rejected?

local Players = game:GetService("Players")
local RStorage = game:GetService("ReplicatedStorage")

local DataStore = game:GetService("DataStoreService")
local MainData = DataStore:GetDataStore("MainData")

local ListOfEvents = {["ExampleGiver"] = RStorage:WaitForChild("ExampleMoneyEvent"),
}

Players.PlayerAdded:Connect(function(plr)
    local playerKey = "id"..plr.UserId
    print("Created ".. playerKey)

    local stats = Instance.new("Folder", plr)
    stats.Name = "leaderstats"

    local cash = Instance.new("IntValue", stats)
    cash.Name = "Cash"

    local LoadProgress = spawn(function()
        repeat wait(.1)
        local success, failure = pcall(function()
            local GetData = MainData:GetAsync(playerKey)
            if GetData then
                print("Data Loaded!")
                cash.Value = GetData
            else
                print("Created New Data!")
                cash.Value = 0
            end
        end)
        until success
    end)


    local EventResponse = spawn(function()
    ListOfEvents.ExampleGiver.OnServerEvent:Connect(function(player, num)
    if typeof(num) == "number" and num >= 0 then
        print("Safely Transferring Funds.")
        player.leaderstats.Cash.Value = player.leaderstats.Cash.Value + num
        print(player.Name.. " currently has ".. cash.Value)
    else
        print"Transfer Invalid."
    end
    end)
    end)

    local SaveProgress = spawn(function()
        while wait(200) do
        MainData:SetAsync(playerKey, cash.Value)
        print("Progress Saved!", "Stats: ", cash.Value, "PlayerInfo: ".. playerKey)
        end
    end)

end)

21:27:39.206 - 502: API Services rejected request with error: HTTP 0 (HTTP 500 (HTTP/1.1 500 Internal Server Error)) 21:27:39.207 - Stack Begin 21:27:39.208 - Script 'ServerScriptService.ExampleConnection', Line 50 21:27:39.209 - Stack End