Why is this breaking?
MWE
\documentclass{memoir}
\begin{document}
test
\end{document}
Log
This is LuaTeX, Version 1.11.2 (TeX Live 2020/dev)
restricted system commands enabled.
(./test.tex
LaTeX2e <2019-10-01> patch level 3
luaotfload | main : initialization completed in 0.123 seconds
(/opt/texlive/2019/texmf-dist/tex/latex/memoir/memoir.cls
Document Class: memoir 2019/11/15 v3.7i configurable book, report, article docu
ment class
(/opt/texlive/2019/texmf-dist/tex/generic/iftex/iftex.sty)
(/opt/texlive/2019/texmf-dist/tex/latex/memoir/mem10.clo)
(/opt/texlive/2019/texmf-dist/tex/latex/tools/array.sty)
(/opt/texlive/2019/texmf-dist/tex/latex/tools/dcolumn.sty)
(/opt/texlive/2019/texmf-dist/tex/latex/tools/delarray.sty)
(/opt/texlive/2019/texmf-dist/tex/latex/tools/tabularx.sty)
! Illegal parameter number in definition of \reserved@a.
<to be read again>
1
l.12970 }
% end of \IfFileExists
?
! Illegal parameter number in definition of \reserved@a.
<to be read again>
2
l.12970 }
% end of \IfFileExists
?
! Illegal parameter number in definition of \reserved@a.
<to be read again>
3
l.12970 }
% end of \IfFileExists
?
! Illegal parameter number in definition of \reserved@a.
<to be read again>
4
l.12970 }
% end of \IfFileExists
?
! Illegal parameter number in definition of \reserved@a.
<to be read again>
1
l.12970 }
% end of \IfFileExists
?
! Illegal parameter number in definition of \reserved@a.
<to be read again>
2
l.12970 }
% end of \IfFileExists
?
! Illegal parameter number in definition of \reserved@a.
<to be read again>
3
l.12970 }
% end of \IfFileExists
?
! Illegal parameter number in definition of \reserved@a.
<to be read again>
4
l.12970 }
% end of \IfFileExists
?
! Illegal parameter number in definition of \reserved@a.
<to be read again>
1
l.12970 }
% end of \IfFileExists
?
! Illegal parameter number in definition of \reserved@a.
<to be read again>
1
l.12970 }
% end of \IfFileExists
?
! Illegal parameter number in definition of \reserved@a.
<to be read again>
1
l.12970 }
% end of \IfFileExists
?
! Illegal parameter number in definition of \reserved@a.
<to be read again>
1
l.12970 }
% end of \IfFileExists
?
! Illegal parameter number in definition of \reserved@a.
<to be read again>
2
l.12970 }
% end of \IfFileExists
?
! Illegal parameter number in definition of \reserved@a.
<to be read again>
3
l.12970 }
% end of \IfFileExists
?
! Illegal parameter number in definition of \reserved@a.
<to be read again>
1
l.12970 }
% end of \IfFileExists
?
! Illegal parameter number in definition of \reserved@a.
<to be read again>
2
l.12970 }
% end of \IfFileExists
?
! Illegal parameter number in definition of \reserved@a.
<to be read again>
3
l.12970 }
% end of \IfFileExists
?
! Illegal parameter number in definition of \reserved@a.
<to be read again>
3
l.12970 }
% end of \IfFileExists
?
! Illegal parameter number in definition of \reserved@a.
<to be read again>
1
l.12970 }
% end of \IfFileExists
?
! Illegal parameter number in definition of \reserved@a.
<to be read again>
1
l.12970 }
% end of \IfFileExists
?
! Illegal parameter number in definition of \reserved@a.
<to be read again>
2
l.12970 }
% end of \IfFileExists
?
! Illegal parameter number in definition of \reserved@a.
<to be read again>
3
l.12970 }
% end of \IfFileExists
?
! Illegal parameter number in definition of \reserved@a.
<to be read again>
1
l.12970 }
% end of \IfFileExists
?
! Illegal parameter number in definition of \reserved@a.
<to be read again>
2
l.12970 }
% end of \IfFileExists
?
! Illegal parameter number in definition of \reserved@a.
<to be read again>
3
l.12970 }
% end of \IfFileExists
?
! Illegal parameter number in definition of \reserved@a.
<to be read again>
3
l.12970 }
% end of \IfFileExists
?
! Illegal parameter number in definition of \reserved@a.
<to be read again>
1
l.12970 }
% end of \IfFileExists
?
! Illegal parameter number in definition of \reserved@a.
<to be read again>
1
l.12970 }
% end of \IfFileExists
?
! Illegal parameter number in definition of \reserved@a.
<to be read again>
1
l.12970 }
% end of \IfFileExists
?
! Illegal parameter number in definition of \reserved@a.
<to be read again>
1
l.12970 }
% end of \IfFileExists
?
! Illegal parameter number in definition of \reserved@a.
<to be read again>
1
l.12970 }
% end of \IfFileExists
?
! Illegal parameter number in definition of \@uclcnotmath.
<to be read again>
{
l.12970 }
% end of \IfFileExists
?
! Illegal parameter number in definition of \MakeTextUppercase .
<to be read again>
1
l.12970 }
% end of \IfFileExists
?
! Illegal parameter number in definition of \MakeTextUppercase .
<to be read again>
2
l.12970 }
% end of \IfFileExists
?
! Illegal parameter number in definition of \MakeTextLowercase .
<to be read again>
2
l.12970 }
% end of \IfFileExists
?
! Illegal parameter number in definition of \MakeTextLowercase .
<to be read again>
1
l.12970 }
% end of \IfFileExists
?
)
No file test.aux.
[1{/opt/texlive/2019/texmf-var/fonts/map/pdftex/updmap/pdftex.map}] (./test.aux)
)
1054 words of node memory still in use:
2 hlist, 1 vlist, 1 rule, 2 glue, 3 kern, 1 glyph, 5 attribute, 178 glue_spe
c, 5 attribute_list, 2 write nodes
avail lists: 2:75,3:7,4:1,5:40,6:7,7:51,9:51
</opt/texlive/2019/texmf-dist/fonts/opentype/public/lm/lmroman10-regular.otf>
Output written on test.pdf (1 page, 2862 bytes).
Transcript written on test.log.