gui

term.clear()
width, height = term.getSize() -- gets the screen size
local progs = {"", "", "" } -- makes a table for use later
local progsrun = {"", "", ""  } -- ^^


function round(val)
  return math.floor(val + 0.5)
  end -- a simple rounding program

function getCenter(length) -- A function that is used to find
  length1 = string.len(length) -- the center of the page
  center = width / 2 - length1 / 2
  return center
end

function title(title) -- A function that is used to generate the title
  term.setCursorPos(getCenter(title), 1)
  term.write(title)
  term.setCursorPos(1, 2)
  local var pos = 1
  while pos <= width do
    term.setCursorPos(pos, 2)
    term.write("_")
    pos = pos + 1
  end
end

function option( optna, optno, totoptno, progtorun, proargs) -- This is the function that is broken somewhere
  local pos = round((height / (totoptno + 1) * optno) + 2 )
  term.setCursorPos(getCenter(optna), pos)
  term.write( optna )
  table.insert(progs, optno, pos) -- This is the table function that im having the problem with as detailed in the OP
  table.insert(progsrun, optno, progtorun) -- The error occurs here too
  -- When activated do
  -- shell.run ( progtorun, progargs )
end

function detect() -- Function to control the cursor
  cursorpos = 1
  while true do
    keyPress = os.pullEvent(char)
      if keyPress == 200 then -- detect key presses and if its the down key
        cursorpos = cursorpos - 1 -- reduce the cursor position by 1
      else if keyPress == 208 then -- oes the opposite
        cursorpos = cursorpos + 1
      else sleep(1)
    end
    if cursorpos < table.getn(progs) then
      cursorpos = cursorpos - 1
    end
    secpos = progs[cursorpos] -- looks at the position of the options based on the variable stored in the table from the option function
    term.setCursorPos( 5, secpos) --
    term.write("-->")
    end
  end
end
title( " Epic GUI " )
option( "Portal Song - Still Alive", 1, 3, "play", "" )
option( "Hey Me", 2, 3, "heyme", "")
option( "cest bien", 3, 3, "optnamd", "")
write(progs[1], progs[2]) -- This is how i found where the error was occuring

detect()