Illegal parameter number

Question

This answer describes a neat way to parse and extract a latex file. It works perfectly on my laptop and desktop (both ubuntu 18.04).

However, when I run the commands in a docker container, I get the error below. The container has textlive-full installed. The container is running Debian Stretch 9.9.

The files tested and instrumenter are in https://tex.stackexchange.com/a/504528/224

studio@704da4b37614:~$ latex '\input instrumenter \input tested'
This is pdfTeX, Version 3.14159265-2.6-1.40.17 (TeX Live 2016/Debian) (preloaded format=latex)
 restricted \write18 enabled.
entering extended mode
LaTeX2e <2017/01/01> patch level 3
Babel <3.9r> and hyphenation patterns for 83 language(s) loaded.
(./instrumenter.tex
(/usr/share/texlive/texmf-dist/tex/latex/l3packages/xparse/xparse.sty
(/usr/share/texlive/texmf-dist/tex/latex/l3kernel/expl3.sty
(/usr/share/texlive/texmf-dist/tex/latex/l3kernel/expl3-code.tex)
(/usr/share/texlive/texmf-dist/tex/latex/l3kernel/l3dvips.def)))) (./tested.tex
 (/usr/share/texlive/texmf-dist/tex/latex/base/report.cls
Document Class: report 2014/09/29 v1.4h Standard LaTeX document class
(/usr/share/texlive/texmf-dist/tex/latex/base/size10.clo)) (./instrumenter.aux)
! Illegal parameter number in definition of \chapter .
<to be read again>
                   3
l.7   \chapter
              [foo]{Foo}
?

Answer 1

The issue was an older version of texlive (v2016) instead of 2017 (or greater).

Updating texlive solved the problem.