Bank/Item Storage GUI Scripting ERROR ~ Doesn't Store item on GUI Button Click?

Recently had this Item Storage GUI when I encountered an error! The error occurs when I click the 4th slot on the GUI which you should see in the code.

The Error I Get Players.ELITE_PUGS.PlayerGui.Bank.Bank.LocalScript:24: invalid argument #3 (string expected, got nil)

Server Script

-- Services --
local Replicated = game:GetService("ReplicatedStorage")
local dataStore = game:GetService("DataStoreService")
local ServerStorage = game:GetService("ServerStorage")

-- DataStores --
local DS2 = require(1936396537);

DS2.Combine("DATA", "Bank")

-- Scripting --
local DEBOUNCES = { }
Replicated[script.Name].OnServerEvent:Connect(function(Player, Slot, retrieveName)
	if (typeof(Slot) ~= "number" or Slot > 4) then return; end
	local playerKey = tostring(Player.UserId) .."_Bank"
	local playerStore = DS2("Bank", Player)
	local playerBase = playerStore:Get({
		[1] = "Empty Slot";
		[2] = "Empty Slot";
		[3] = "Empty Slot";	
		[4] = "Empty Mom";
	});
	if (not retrieveName) then
		if (DEBOUNCES[Player.Name]) then return; end
		DEBOUNCES[Player.Name] = true
		if (playerBase[Slot] == "Empty Slot") then
			local ITEM = Player.Character:FindFirstChildOfClass("Tool");
			if (not ITEM) then
				Replicated[script.Name]:FireClient(Player, Slot, "Read instructions!")
				wait(1)
				Replicated[script.Name]:FireClient(Player, Slot, playerBase[Slot])
			elseif (ITEM) then
				playerBase[Slot] = ITEM.Name;
				ITEM:Destroy()
				Replicated[script.Name]:FireClient(Player, Slot, playerBase[Slot])
				playerStore:Set(playerBase)
			end
		else
			local ITEM = ServerStorage:FindFirstChild(playerBase[Slot])
			if (ITEM) then
				local CLONE = ITEM:Clone()
				CLONE.Parent = Player.Backpack
			end
			playerBase[Slot] = "Empty Slot";
			Replicated[script.Name]:FireClient(Player, Slot, playerBase[Slot])
			playerStore:Set(playerBase)
			
		end
		
		DEBOUNCES[Player.Name] = false
	elseif (retrieveName) then
		Replicated[script.Name]:FireClient(Player, tostring(Slot), playerBase[Slot])
	end
end)

Local Script in GUI

-- Services --
local Replicated = game:GetService("ReplicatedStorage")
local Players = game:GetService("Players")

-- LocalPlayer --
local Player = Players.LocalPlayer

-- Scripting --
for _, b in pairs(script.Parent:GetChildren()) do
	coroutine.resume(coroutine.create(function()
		if (b:IsA("TextButton")) then
			Replicated["Bank"]:FireServer(tonumber(b.Name), true)
			b.MouseButton1Click:Connect(function()
				Replicated["Bank"]:FireServer(tonumber(b.Name), false)
			end)
		end
	end))
end
Replicated["Bank"].OnClientEvent:Connect(function(Slot, Text)
	script.Parent[Slot].Text = Text; -- Error = Players.ELITE_PUGS.PlayerGui.Bank.Bank.LocalScript:24: invalid argument #3 (string expected, got nil)
end)