Lua - unexpected symbol

Question

My code gives "script.lua:25: unexpected symbol". I am trying to make a app for the PSP with lua and it gives the error.

What's wrong with my code?

usb.on()
green = color.new(0, 255, 0)
blue = color.new(0, 0, 255)
white = color.new(255, 255, 255)
screen.print(200, 100, "Hello World!" .. tostring(os.clock()), green)
screen.flip()

while true do
    index = 0
    screen.print(0, 10, tostring(batt.percent()) .. "%", white)

    for i in pairs(files.listfiles("/")) do
        screen.print(0, index * 10, i, white)
        index = index + 1
    end

    for i = 0, 20 do
        x0 = i / 20 * 479
        y1 = 271 - i / 20 * 271
        draw.line(x0, 271, 479, y1, blue)
    end

    screen.flip()
    
end

Answer 1

I solved it! The code itself doesn't have errors. I fixed it with a reboot of the interpreter