
I’m the maintainer of the nodetree package. I got a bug report: https://github.com/Josef-Friedrich/nodetree/issues/46 I was able to narrow down the problem: debug.tex: \documentclass{article} \begin{document} \directlua{ luatexbase.add_to_callback('vpack_filter', function(head) if node.type(head.id) == 'whatsit' and head.subtype == 1 then local tmp = head.data end return true end, 'debug' ) } \begin{figure} \caption{test} \end{figure} \end{document} lualatex debug.tex: ! Incomplete \iffalse; all text was ignored after line 19. <inserted text> \fi l.19 \end{figure} The line 'local tmp = head.data' causes the error. I tried also 'print(head.data)' or 'local tmp = head['data']'. These access types also caused a crash. Access to fields other than data works without any problems. print(head.stream) print(head.id) print(head.xxx) Is this a bug in LuaTeX? Or how can I access the field 'data' of a whatsit(write) node for debugging purposes?