[metapost] luamplib + textext + empty string = bug ?

[Dohyun Kim]

2021년 9월 16일 (목) 오전 5:32, Toby Thurston <thurston at eml.cc>님이 작성:
>
> \documentclass{standalone}
> \usepackage{luamplib}
> \begin{document}
> \mplibtextextlabel{enable}
> \begin{mplibcode}
> beginfig(1);
>     label(mpversion, origin);
>     label("", 10 up);
> endfig;
> \end{mplibcode}
> \end{document}
>
> Then it fails with an error, no output it produced, and I see this in the log
>
> ...texlive/2021/texmf-dist/tex/luatex/luamplib/luamplib.lua:22: bad argument #2
> to 'format' (no value)
> stack traceback:
> [C]: in function 'string.format'
> ...texlive/2021/texmf-dist/tex/luatex/luamplib/luamplib.lua:22: in upvalue 'war
> n'
> ...texlive/2021/texmf-dist/tex/luatex/luamplib/luamplib.lua:257: in upvalue 're
> porterror'
> ...texlive/2021/texmf-dist/tex/luatex/luamplib/luamplib.lua:313: in function <.
> ..texlive/2021/texmf-dist/tex/luatex/luamplib/luamplib.lua:309>
> (...tail calls...)
> ...texlive/2021/texmf-dist/tex/luatex/luamplib/luamplib.lua:656: in field 'proc
> ess_mplibcode'
> [\directlua]:1: in main chunk.
> <inserted text> BAD
>
>

Your luamplib version seems to be out-of-date; the error message on my
side is different from yours.
Anyway, I just uploaded to CTAN a new version of luamplib in which
empty string in textext is allowed.
Thanks for the report.

-- 
Dohyun Kim
Seoul, Republic of Korea