attempt to index nil with 'Name'?

game.Players.PlayerAdded:Connect(function(player)
    local leaderstats = Instance.new('Folder', player)
    leaderstats.Name = 'leaderstats'

    local Pet = Instance.new('Folder', player)
    Pet.Name = 'Pet'

    local coins = Instance.new("IntValue", leaderstats)
    coins.Name = 'Coins'
    coins.Value = 0

    player.CharacterAdded:connect(function(char)
        local attachment = Instance.new("Attachment", char.HumanoidRootPart)
        attachment.Name = "CharacterAt"

    end)
end)





game.ReplicatedStorage.Remotes.Add.OnServerEvent:Connect(function(player)
    local currency = 'Coins'
    local ammount = 1

    player.leaderstats[currency].Value = player.leaderstats[currency].Value +  ammount


end)  

game.ReplicatedStorage.RemoteFunctions.EquipPet.OnServerInvoke = function(player, pet)


    local currency = "Coins"
    local MainPet = game.ServerStorage.Pets:FindFirstChild(pet)

    if not player.Pet:FindFirstChild(MainPet.Name) then
        if player.leaderstats[currency].Value >= MainPet.Price.Value then
            player.leaderstats[currency].Value = player.leaderstats[currency].Value - MainPet.Price.Value
            local clonedPet = MainPet:Clone()
            local atPet = Instance.new("Attachment", clonedPet.PrimaryPart)

            local ap = Instance.new ("AlignPosition")
            ap.Parent = pet 
            ap.RigdigityEnabled = true 
            clonedPet.Parent = player.Character
            clonedPet:SetPrimaryPartCFrame(player.Character.Head.Cframe)
            ap.Attachment0 = atPet
            ap.Attachment1 = player.Character.HumanoidRootPart.CharacterAt




            return "Bought"
        else
            return "Not enough coins"

        end
    else
        return "Equip"
    end
end

Problem error ServerScriptService.Main:38: attempt to index nil with 'Name' - Server - Main:38

ServerScriptService.Main:38: attempt to index nil with 'Name' - Client - LocalScript:2 Local Script

script.Parent.MouseButton1Click:Connect(function()
    local result = game.ReplicatedStorage.RemoteFunctions.EquipPet:InvokeServer(script.Parent.Parent.Name)
end)

Note: The code stops at this line - if not player.Pet:FindFirstChild(MainPet.Name) then