[NTG-context] LuaMetaTex dereferences NULL pointer

[Marcel Fabian Krüger]

Hi,

with the latest LuaMetaTeX upload (running on Linux x64),
\normalunexpanded tries to write to address 0 and therefore
segfaults:

\normalunexpanded{abc}
\starttext
\stoptext

ConTeXt fails with

mtx-context     | fatal error: return code: 139

The most interesting message from valgrind is

==53200== Invalid write of size 4
==53200==    at 0x17113D: ??? (in /home/marcel/lmtx-install/tex/texmf-linux-64/bin/luametatex)
==53200==    by 0x151625: ??? (in /home/marcel/lmtx-install/tex/texmf-linux-64/bin/luametatex)
==53200==    by 0x151E40: ??? (in /home/marcel/lmtx-install/tex/texmf-linux-64/bin/luametatex)
==53200==    by 0x15E1A2: ??? (in /home/marcel/lmtx-install/tex/texmf-linux-64/bin/luametatex)
==53200==    by 0x154AA1: ??? (in /home/marcel/lmtx-install/tex/texmf-linux-64/bin/luametatex)
==53200==    by 0x122347: ??? (in /home/marcel/lmtx-install/tex/texmf-linux-64/bin/luametatex)
==53200==    by 0x4A0C151: (below main) (in /usr/lib/libc-2.32.so)
==53200==  Address 0x0 is not stack'd, malloc'd or (recently) free'd
==53200== 
==53200== 
==53200== Process terminating with default action of signal 11 (SIGSEGV): dumping core
==53200==  Access not within mapped region at address 0x0
==53200==    at 0x17113D: ??? (in /home/marcel/lmtx-install/tex/texmf-linux-64/bin/luametatex)
==53200==    by 0x151625: ??? (in /home/marcel/lmtx-install/tex/texmf-linux-64/bin/luametatex)
==53200==    by 0x151E40: ??? (in /home/marcel/lmtx-install/tex/texmf-linux-64/bin/luametatex)
==53200==    by 0x15E1A2: ??? (in /home/marcel/lmtx-install/tex/texmf-linux-64/bin/luametatex)
==53200==    by 0x154AA1: ??? (in /home/marcel/lmtx-install/tex/texmf-linux-64/bin/luametatex)
==53200==    by 0x122347: ??? (in /home/marcel/lmtx-install/tex/texmf-linux-64/bin/luametatex)
==53200==    by 0x4A0C151: (below main) (in /usr/lib/libc-2.32.so)
==53200==  If you believe this happened as a result of a stack
==53200==  overflow in your program's main thread (unlikely but
==53200==  possible), you can try to increase the size of the
==53200==  main thread stack using the --main-stacksize= flag.
==53200==  The main thread stack size used in this run was 8388608.

Best regards,
Marcel