This toggle MATERIALS gui doesn't seem to work?

The objects are a table,

local players = game:GetService('Players')


local localplayer = players.LocalPlayer
local char = localplayer.Character or localplayer.CharacterAdded:wait()
repeat wait() until char:WaitForChild("Head")
local togglebutton = script.Parent

local materials = true
local smoothplastic = Enum.Material.SmoothPlastic
local objects = {}

wait(4)
local function scan(object)

for i,v in pairs(object:GetDescendants()) do
if v:IsA("Part") and v.Material then
table.insert(objects, v.Material)
end
end
	
end

scan(game.Workspace)

togglebutton.MouseButton1Click:Connect(function()
	materials = not materials
	if materials then
		

			for i, v in pairs(game.Workspace:GetDescendants()) do
	if v:IsA("Part") or v:IsA("UnionOperation") and v.Material then
		v.Material=objects[i]
	end
end

		togglebutton.Text = 'UNTOGGLE LOW GFX MODE'
	else
		for i, v in pairs(game.Workspace:GetDescendants()) do
	if v:IsA("Part") or v:IsA("UnionOperation")  then
		v.Material=Enum.Material.SmoothPlastic
	end
end
		togglebutton.Text = 'TOGGLE LOW GFX MODE'
	end
end)

I'm trying to make it so you can toggle materials, but it doesn't seem to work. Any advices? The error in the output says: 14:47:03.544 - > Invalid value for enum Material Oh yeah, extra informations, the objects part is a table {} with materials in it. But it says It's a value, how can I fix this?