# LuaTeX nil value errors

I tried to lualatex a document and got the following error:

! LuaTeX error ./luasseq.lua:377: attempt to index field 'wd' (a nil value)
stack traceback:
./luasseq.lua:377: in function 'sseq_register_size'
<\directlua >:1: in main chunk.
l.2 \directlua0{sseq_register_size()}

l.373 \end{sseq}}
\end{center}


When I compiled the document at the beginning of May, this error didn't appear, and I haven't edited it since then (though I did upgrade from Ubuntu 10.10 to 11.04 in the meantime).

1. Does anyone know what this error means?

2. Any ideas how this error exists now when it didn't before? Has anyone else had problems with LuaTeX since updating Ubuntu? (I am certain the error was not there before because the document is an essay which I debugged and handed in before upgrading and haven't looked at since.)

Edit:

MWE:

\documentclass{article}
\usepackage{amsmath}
\usepackage{luasseq}
\begin{document}
\mbox{
\begin{sseq}{0...3}{0...2}
\ssdrop{Z}
\end{sseq}}
\end{document}


The error message (quoted above) refers to line 377 of luasseq.lua, which reads

currobj.wd = tex.wd[sseqboxno]


So if tex.wd doesn't exist anymore, does that mean I need an updated version of luasseq.lua? I haven't found one -- does anyone know if it exists?

Oh, and luatex --version gives me

a@dell:~\$ luatex --version
This is LuaTeX, Version beta-0.65.0-2011041019 (rev 4033)
Copyright 2010 Taco Hoekwater, the LuaTeX Team.

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Please add a minimal working example (MWE) that illustrates your problem. –  Caramdir Jul 26 '11 at 0:36
As far as I know Ubuntu 10.10 and 11.04 use the same (outdated) version of LuaTeX. –  Caramdir Jul 26 '11 at 0:37
If you had a custom install of e.g. TeXlive instead of the outdated one shipping with Ubuntu, you might have clobbered it when upgrading Ubuntu and ended up with an older luatex? Can you give the first and last line of luatex --version? (and an MWE) –  Bruno Le Floch Jul 26 '11 at 6:28

The wd hints at the use of tex.wd, a field that does not exist any more in current versions of luatex. So, it looks like you now have a new luatex, but are running macros for a previous version. These should be updated as well.

I do not know of a new version of luasseq.lua, but replacing the problematic line and the two following ones with

currobj.wd = tex.box[sseqboxno].width
currobj.ht = (tex.box[sseqboxno].height+tex.box[sseqboxno].depth)
currobj.dp = tex.box[sseqboxno].depth


apparently fixes the problem.

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That did indeed fix the problem. Thank you! –  Adina G Jul 26 '11 at 19:22