attempt to index ? (a nil value)

Hello~

So basically I am setting up a mob farm in FTB CrackPack. I've never made a mob farm before, so I went on YouTube and found a very nice tutorial that utilizes ComputerCraft to control the mob farm.

Using this to program to control the mob farm: http://pastebin.com/qhTZLiKF
Getting this error: https://i.gyazo.com/...b5029caa1fc.png
Followed this video tutorial to the T: https://www.youtube....h?v=5xPHGwJxgP8

The guy in the video didn't get any errors, and I don't see what's wrong with line 44:

mon.setBackgroundColor(defaultBgColor)

Maybe someone else can see it. xD
Thanks for reading!

Do you actually have a monitor on top of the computer?

Dog, on 10 November 2016 - 04:01 PM said:

Do you actually have a monitor on top of the computer?

No, the computer is on the left of the monitor, and I editted the program to reflect this already.

peripheral.wrap("top") means to the computer "the monitor is on the top of the computer" if its on the left, change top to left (or what side the monitor is on)

Unless I've missed something…



Looks like you should be calling `peripheral.wrap( side )` instead.

The error was because you were calling the monitor function, when a monitor was nonexistant. What you should do instead is

if not mon then
  printError("Please change the monitor side in the program")
  printError("config,  then try again.")
  return
end

Add this to the top, that way you will know if the bug will happen again