[HELP] Stop Players from picking up Tools?

So i got this Backpack Gui, it creates slots (10) where tools go, when a Player picks them up. My Problem now is that if a player has 11 Tools and he drops one of those 10, which are shown, the 11 tool is just gone. it isnt going automaticly in the missing Slot. I just cant access the 11 Tool.

Any way to put the tool automaticly in the missing field? or stop the players from picking up Tools, when he is full (10 tools)?

game:GetService('StarterGui'):SetCoreGuiEnabled(Enum.CoreGuiType.Backpack, false)

 --< variables >--
local uis = game:GetService("UserInputService")
local player = game.Players.LocalPlayer
local char = workspace:WaitForChild(player.Name) -- added WaitForChild
local bp = player.Backpack
local hum = char:WaitForChild("Humanoid")
local frame = script.Parent.Frame
local template = frame.Template
local equipped = 0.7 -- icon transparencies
local unequipped = 0.2

local iconSize = template.Size
local iconBorder = {x = 15, y = 5} -- pixel space between icons

local inputKeys = { -- dictionary for effective referencing
    ["One"] = {txt = "1"},
    ["Two"] = {txt = "2"},
    ["Three"] = {txt = "3"},
    ["Four"] = {txt = "4"},
    ["Five"] = {txt = "5"},
    ["Six"] = {txt = "6"},
    ["Seven"] = {txt = "7"},
    ["Eight"] = {txt = "8"},
    ["Nine"] = {txt = "9"},
    ["Zero"] = {txt = "0"},
}

local inputOrder = { -- array for storing the order of the keys
    inputKeys["One"],inputKeys["Two"],inputKeys["Three"],inputKeys["Four"],inputKeys["Five"],
    inputKeys["Six"],inputKeys["Seven"],inputKeys["Eight"],inputKeys["Nine"],inputKeys["Zero"],
}

--< functions >--
function handleEquip(tool)
    if tool then
        if tool.Parent ~= char then
            hum:EquipTool(tool)
        else
            hum:UnequipTools()
        end
    end
end

function create() -- creates all the icons at once (and will only run once)

    local toShow = #inputOrder -- # operator can only be used with an array, not a dictionary
    local totalX = (toShow*iconSize.X.Offset)+((toShow+1)*iconBorder.x)
    local totalY = iconSize.Y.Offset + (2*iconBorder.y)

    frame.Size = UDim2.new(0, totalX, 0, totalY)
    frame.Position = UDim2.new(0.5, -(totalX/2), 1, -(totalY+(iconBorder.y*2)))
    frame.Visible = true -- just in case!

    for i = 1, #inputOrder do

        local value = inputOrder[i]     
        local clone = template:Clone()
        clone.Parent = frame
        clone.Label.Text = value["txt"]
        clone.Name = value["txt"]
        clone.Visible = true
        clone.Position = UDim2.new(0, (i-1)*(iconSize.X.Offset)+(iconBorder.x*i), 0, iconBorder.y)
        clone.ImageTransparency = unequipped

        local tool = value["tool"]
        if tool then
            clone.Tool.Image = tool.TextureId
        end

        clone.Tool.MouseButton1Down:Connect(function() -- click icon to equip/unequip
            for key, value in pairs(inputKeys) do
                if value["txt"] == clone.Name then
                    handleEquip(value["tool"]) 
                end 
            end
        end)

    end 
    template:Destroy()
end

function setup() -- sets up all the tools already in the backpack (and will only run once)
    local tools = bp:GetChildren()
    for i = 1, #tools do 
        if tools[i]:IsA("Tool") then -- does not assume that all objects in the backpack will be a tool (2.11.18)
        for i = 1, #inputOrder do
            local value = inputOrder[i]
            if not value["tool"] then -- if the tool slot is free...
                value["tool"] = tools[i]    
                break -- stop searching for a free slot
            end
        end
        end
    end
    create()
end

function adjust()
    for key, value in pairs(inputKeys) do
        local tool = value["tool"]
        local icon = frame:FindFirstChild(value["txt"])
        if tool then
            icon.Tool.Image = tool.TextureId
            if tool.Parent == char then -- if the tool is equipped...
                icon.ImageTransparency = equipped
            else
                icon.ImageTransparency = unequipped
            end
        else
            icon.Tool.Image = ""
            icon.ImageTransparency = unequipped
        end
    end
end

function onKeyPress(inputObject) -- press keys to equip/unequip
    local key = inputObject.KeyCode.Name
    local value = inputKeys[key]
    if value and uis:GetFocusedTextBox() == nil then -- don't equip/unequip while typing in text box
        handleEquip(value["tool"])
    end 
end

function handleAddition(adding)

    if adding:IsA("Tool") then
        local new = true

        for key, value in pairs(inputKeys) do
            local tool = value["tool"]
            if tool then
                if tool == adding then
                    new = false
                end
            end
        end

        if new then
            for i = 1, #inputOrder do
                local tool = inputOrder[i]["tool"]
                if not tool then -- if the tool slot is free...
                    inputOrder[i]["tool"] = adding
                    break
                end
            end
        end

    adjust()
    end
end

function handleRemoval(removing) 
    if removing:IsA("Tool") then
        if removing.Parent ~= char and removing.Parent ~= bp then

            for i = 1, #inputOrder do
                if inputOrder[i]["tool"] == removing then
                    inputOrder[i]["tool"] = nil
                    break
                end
            end
        end

        adjust()
    end
end

--< events >--
uis.InputBegan:Connect(onKeyPress)

char.ChildAdded:Connect(handleAddition)
char.ChildRemoved:Connect(handleRemoval)

bp.ChildAdded:Connect(handleAddition)
bp.ChildRemoved:Connect(handleRemoval)

--< start >--
setup()