Origin of Lua Error

Question

If a lualatex compilation breaks with/at this terminal output:

(/usr/local/texlive/2022/texmf-dist/tex/generic/pgf/utilities/pgfkeysfiltered.c
ode.tex))[\directlua]:1: attempt to call a nil value (field 'get_functions_tabl
e').
l.1738   }

Does it mean the failing \directlua is in /usr/local/texlive/2022/texmf-dist/tex/generic/pgf/utilities/pgfkeysfiltered.code.tex?

Thing is, that file does not contain a directlua. OTOH this error only started o appear after I got lualatex to read and parse an additional Lua file within my personal document infrastructure -- but I don't see anything suspicious of being related in that additional file either.

Answer 1

You provided no example, but given a guessed example

\documentclass{article}

\usepackage{tikz}

\begin{document}

\end{document}

The relevant part of the terminal output is

(/usr/local/texlive/2022/texmf-dist/tex/latex/pgf/systemlayer/pgfsys.sty
(/usr/local/texlive/2022/texmf-dist/tex/generic/pgf/systemlayer/pgfsys.code.tex
(/usr/local/texlive/2022/texmf-dist/tex/generic/pgf/utilities/pgfkeys.code.tex
(/usr/local/texlive/2022/texmf-dist/tex/generic/pgf/utilities/pgfkeysfiltered.c
ode.tex))

The penultimate ) shows that pgfkeysfiltered.code.tex has been read to the end, so the final ) shown shows that pgfkeys.code.tex has been read to the end, so any line number in an error message at this point refers to the file at the top of the stack of open files, which is pgfsys.code.tex, line 1738 of which is the closing } of this \directlua call

  \directlua{
  local lft = lua.get_functions_table()
  lft[\string#lft+1] = function()
      local lhs = token.scan_string()
      local rhs = token.scan_string()
      if lhs < rhs then
          tex.sprint(-2, "-1")
      elseif lhs == rhs then
          tex.sprint(-2, "0")
      else
          tex.sprint(-2, "1")
      end
  end
  token.set_lua("pgfsys@strcmp", \string#lft, "global")
  }