Attempted to index a nil value?

I get the following error when I try to update the display that tells the player how much money they have:

19:15:32.798 - ServerScriptService.DataManager:47: attempt to index field '?' (a nil value)
19:15:32.798 - Stack Begin
19:15:32.799 - Script 'ServerScriptService.DataManager', Line 47
19:15:32.800 - Stack End

Script inside the serverscriptservice:

local DS = game:GetService("DataStoreService")
local Players = game:GetService("Players")
local Run = game:GetService("RunService")

local playerDataStore = DS:GetDataStore("PlayerData")

local PlayerSesStats = {} -----Player data on current session
local LoadedPlayers = {} -----Players whose data has already been loaded

local UpdEve = game.ReplicatedStorage.UpdateCash

local function DefaultStats()
    return {
        Money = 100
    }
end

local function UpdateCash(player, amount)
    UpdEve:FireClient(player, amount)
end

local function GuestCheck(player) -----Checks wether or not the player is a Guest
    return Run:IsStudio() and player.UserId < 1
end

local function OnPlayerAdded(player)

    local userid = player.UserId

    if LoadedPlayers[userid] then -----Checks wether or not the user's data has been loaded on the current server
        player:Kick("An error occured when attempting to fetch your player data. Please wait a few seconds and rejoin.")
        return
    end

    if not GuestCheck(player) then
        local loadSuccess, LoadedData = pcall(function() return playerDataStore:GetAsync(player.UserId) end) ----- Returns the player's datastore and wether or not it succeeded in that.

    if loadSuccess and LoadedData then
        if LoadedData == nil or LoadedData == {} then
            PlayerSesStats[player.UserId] = DefaultStats()
        else 
            PlayerSesStats[player.UserId] = LoadedData
        end     
    end
    end

    UpdateCash(player, PlayerSesStats[player.UserId].Money)
end

local function OnPlayerRemoved(player)
    if not LoadedPlayers[player.UserId] then
        return
    end

    local SaveData = PlayerSesStats[player.UserId]

    pcall(function()
        playerDataStore:SetAsync(player.UserId, SaveData)
    end)
    LoadedPlayers[player.UserId] = nil
end

local function OnServerShutdown()
    local Players = Players:GetPlayers()

    for index = 1, #Players do
        local player = Players[index]
        OnPlayerRemoved(player)
    end
end


Players.PlayerAdded:Connect(OnPlayerAdded)
Players.PlayerRemoving:Connect(OnPlayerRemoved)

game:BindToClose(OnServerShutdown)

The script that updates the player's currency display:

local Display = script.Parent.MainGui.CashBox.Cash
local UpdEve = game.ReplicatedStorage.UpdateCash

UpdEve.OnClientEvent:Connect(function(amount)
    Display.Text = amount
end)

What is causing the error and how do I fix it? And by the way, am I doing datascripts right so far?