Script Detects StringValue as a Table. Why and how do i fix it?

I have a AutoShutdownScript on my game that was not made by me and it has an error. A value is detected as a table, not a string value as it is supposed to be.

if placeId == 0 then script:Destroy() end -- No proper info.
local market = game:WaitForChild("MarketplaceService")
local serverVersion = Instance.new("StringValue",game) --This is the StringValue that is detected as a table

serverVersion.Value = market:GetProductInfo(placeId) --This line is where it errors
serverVersion.Name = "SERVER_VERSION"

while true do --Extra code in the script if you want to see it
    game:GetService("RunService").Stepped:wait()
    local currentVersion = market:GetProductInfo(placeId)
    if currentVersion ~= serverVersion.Value then
        if manualShutDown ~= true then
            local m = Instance.new("Message",workspace)
            m.Text = "This game has been updated! Shutting down server..."
            wait(1)
            Instance.new("ManualSurfaceJointInstance",workspace)
        else
            local f,s = string.find(currentVersion,"autoshutdown:go")
            if f ~= nil and s ~= nil then
                local m = Instance.new("Message",workspace)
                m.Text = "This game has been updated! Shutting down server..."
                wait(1)
                Instance.new("ManualSurfaceJointInstance",workspace)
            end
        end
    end
end                                                                                                                         

Please Help