restricted system commands enabled.
(./lua-linebreak-filter.tex
LBF false prevdepth=131072 prevgraf=0 mode=1
Underfull \hbox (badness 10000) in paragraph at lines 22--22
[]\f Some
Underfull \hbox (badness 252) in paragraph at lines 22--22
\f words in a paragraph
Underfull \hbox (badness 1997) in paragraph at lines 22--22
\f that will be broken.
POST [0] [0]
! OK (see the transcript file).
l.23 \showlists
[0]
LBF false prevdepth=131072 prevgraf=0 mode=1
POST
> 2.0pt.
l.25 \showthe\prevdepth
\showthe\prevgraf
> 0.
l.25 \showthe\prevdepth \showthe\prevgraf
[0]
LBF true prevdepth=131072 prevgraf=0 mode=1
Underfull \hbox (badness 10000) in paragraph at lines 26--26
[]\f Some words
POST math_shift
! \textfont1 is undefined (character 120).
l.26 \directlua{CASE = 6}Some words $$x$$
more words.\par
[0]
LBF false prevdepth=0 prevgraf=3 mode=1
Underfull \hbox (badness 10000) in paragraph at lines 26--26
\f more words.
POST
! OK (see the transcript file).
l.27 \showlists
[0] [0]
LBF false prevdepth=0 prevgraf=0 mode=1
! Invalid linebreak_filter.
l.28 \directlua{CASE = 5}Some words.\par
! ==> Fatal error occurred, bad output DVI file produced!
Output written on lua-linebreak-filter.dvi (7 pages, 648 bytes).
Transcript written on lua-linebreak-filter.log.