ServerScriptService.leaderstats:87: attempt to index nil with 'leaderstats

Question

So basically I'm making a roblox clicker simulator game and sometimes when I test the save data for clicks it sometimes gives me this error ServerScriptService.leaderstats:87: attempt to index nil with 'leaderstats'

    local success, errormessage = pcall(function()
        rebirthsDataStore:SetAsync(playerUserId, rebirthsValue)
    end)
    
    -- Saving Gems Data
    local gemsValue = player.leaderstats.Gems.Value

    local success, errormessage = pcall(function()
        gemsDataStore:SetAsync(playerUserId, gemsValue)
    end)
end)

game:BindToClose(function(player)
    for _, Player in pairs(game.Players:GetPlayers()) do

        local playerUserId = "player"..Player.UserId
        
        -- Saving Clicks
        local clicksValue = player.leaderstats.Clicks.Value
        local success, errormessage = pcall(function()
            clicksDataStore:SetAsync(playerUserId, clicksValue)
        end)
        -- Saving Rebirths
        local rebirthsValue = player.leaderstats.Rebirths.Value

        local success, errormessage = pcall(function()
            rebirthsDataStore:SetAsync(playerUserId, rebirthsValue)
        end)

        -- Saving Gems Data
        local gemsValue = player.leaderstats.Gems.Value

        local success, errormessage = pcall(function()
            gemsDataStore:SetAsync(playerUserId, gemsValue)
        end)
    end
end) 

Answer 1

Your error is telling you that when you try to access player.leaderstats, the player variable doesn't have a value. And this is because the game:BindToClose function does not provide a Player as an argument.

But you are iterating over all of the Players left in the server in a for-loop, just set the name of that iterator variable to be player and make sure the capitalization is correct in the rest of your code.

game:BindToClose(function()
    for _, player in ipairs(game.Players:GetPlayers()) do
        local playerUserId = "player" .. player.UserId