Leaderstats With DataStore Failure?

When a value incercrases, it doesn't saves with DataStore, here is the script:

local DataStoreService = game:GetService("DataStoreService")

local myDataStore = DataStoreService:GetDataStore("myDataStore")

 -- Creates a leaderboard that shows player variables
    local function onPlayerJoin(player)
    	local leaderstats = Instance.new("Folder")
    	leaderstats.Name = "leaderstats"
    	leaderstats.Parent = player
     
    	local gold = Instance.new("IntValue")
    	gold.Name = "Gold"
    	gold.Value = 0
    	gold.Parent = leaderstats
     
    	local items= Instance.new("IntValue")
    	items.Name = "Molecules"
    	items.Value = 0
    	items.Parent = leaderstats
     
    	local spaces = Instance.new("IntValue")
    	spaces.Name = "Spaces"
    	spaces.Value = 2
    	spaces.Parent = leaderstats
     
    end
     
    -- Run onPlayerJoin when the PlayerAdded event fires
    game.Players.PlayerAdded:Connect(onPlayerJoin)



local data      
local success, errormessage = pcall(function()
	myDataStore:GetAsync(player.UserId.."-items")
		myDataStore:GetAsync(player.UserId.."-spaces")
			myDataStore:GetAsync(player.UserId.."-gold")
    end)

game.Players.PlayerRemoving:Connect(function(player)
	
	local success, errormessage = pcall(function()
	data = myDataStore:SetAsync(player.UserId.."-",player.leaderstats.gold.Value)
	
	data = myDataStore:SetAsync(player.UserId.."-",player.leaderstats.items.Value)
	
	data = myDataStore:SetAsync(player.UserId.."-",player.leaderstats.spaces.Value)
end)

if success then

gold.Value = data
items.Value = data
spaces.Value = data
else
	print("Unexcepted Error Happened while saving your data! ")
	warn(errormessage)

end
      
if success then
print ("playerdatasaved")
	else
	print ("playerdatanotsaved")
	warn(errormessage)
	end
end)

First things first, "player" in lines 35-37 is not defined anywhere. Script doesn't understand what 'player' is.

Second, "gold", "items" and "spaces" in lines 52-54 are also not defined. Even if you create a variable in function, it doesn't work outside it.

I think your problem is, that you don't understand how to use scopes. Here's a Roblox tutorial about it: https://developer.roblox.com/en-us/articles/Scope

Also, there's a nice Roblox tutorial that explains how to correctly save player's data on exit: https://developer.roblox.com/en-us/articles/Saving-Player-Data

Making it the way you've done it is a bad practice. After player leaves the game script can't access "leaderstats" object, because it's already gone. You should do this the way as it's shown in the second link :)

And also, when you test DataStore, I recommend doing it in actual game, not in Roblox Studio. DataStore in Roblox Studio doesn't always work with game.Players.PlayerRemoving.

Hope I helped :)