How to fix? ServerScriptService.Main:30: attempt to index nil with 'Name' - Client - LocalScript:2

This is the second time i have posted this. Someone please help. So the problem is, I have a pet store, when you walk over it a gui comes up very well there is a scrolling place there is a close button. But when you try to press the buy button and you have enough money It comes up with this error 'ServerScriptService.Main:30: attempt to index nil with 'Name' - Client - LocalScript:2' and does nothing.

LocalScript:2

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

ServerScirptService Main:

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

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

    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'
        attachment.Position = Vector3.new(3,3,0)
    end)
end)


game.ReplicatedStorage.Remotes.Add.OnServerEvent:Connect(function(player, ammount)
    local currency = 'Coins'
    local ammount = 1000
    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.Pets: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()
            clonedPet.Parent = player.Character
            clonedPet:SetPrimaryPartCFrame(player.Character.Head.CFrame)

            local atPet = Instance.new('Attachment', clonedPet.PrimaryPart)

            local ap = Instance.new('AlignPosition')
            ap.Parent = clonedPet
            ap.RigidityEnabled = true
            ap.Attachment0 = atPet
            ap.Attachment1 = player.Character.HumanoidRootPart.CharacterAt

            return 'Bought'
        else
            return 'Not enough coins'
        end
    else
        return 'Equip'
    end
end