"index expected, got nil" without an array anywhere

Yet another problem with my Interaction API and this time it's complaining about me using a table term when I am not using any tables.
This is one line 3 of the code, click the link above to go to the pastebin.
This used to work, but for some reason doesn't… and it started ever since I implemented interaction.drawButton() which is further down.

~Hydro

You have to create a list, before you can declare functions in it:

prognam = shell.getRunningProgram()
screenX, screenY = term.getSize()
_G["interact"] = {} --You haven't use _G, if you want to use your API just in the normal shell or higher instances.
function interact.centertext(text,ypos)
  local char = tostring(text)
  local chars = string.len(char)
  local hchars = math.floor(chars / 2)
  local xpos = math.ceil((screenX / 2) - hchars)
  term.setCursorPos(xpos,ypos)
  print(text)
end

Ta :)/>

is this because i set it in interact.(funcname)?
I'm usually used to just making function names so this is the first time i've actually added a catagory to the functions.

Hydrotronics, on 24 February 2016 - 07:03 PM said:

Ta :)/>

is this because i set it in interact.(funcname)?
I'm usually used to just making function names so this is the first time i've actually added a catagory to the functions.

Yes, you add with interact[string name] a value into the table interact, so you have to declare the table before.
Tables are very powerful types (click here for more information).

The syntax a.b is equivalent to a[ "b" ]. In other words, it accesses the table a with the key b.

Also, do not confuse tables with lists. They are tables. There are no lists in Lua.