Running `Preview-LaTeX' on `~/junk/_region_' with ``lualatex  -interaction=nonstopmode -file-line-error &prv_test "/AUCTEXINPUT{" _region_.tex "}"''
This is LuaTeX, Version 1.07.0 (TeX Live 2018/Arch Linux)
 restricted system commands enabled.

kpathsea: Running mktexfmt prv_test.fmt
mktexfmt: mktexfmt is using the following fmtutil.cnf files (in precedence order):
mktexfmt:   /etc/texmf/web2c/fmtutil.cnf
mktexfmt: mktexfmt is using the following fmtutil.cnf file for writing changes:
mktexfmt:   /home/berber/.texlive/texmf-config/web2c/fmtutil.cnf
mktexfmt [INFO]: writing formats under /home/berber/.texlive/texmf-var/web2c
mktexfmt [INFO]: did not find entry for byfmt=prv_test, skipped
mktexfmt [INFO]: Disabled formats: 6
mktexfmt [INFO]: Not selected formats: 36
mktexfmt [INFO]: Total formats: 42
mktexfmt [INFO]: exiting with status 0
Sorry, I can't find the format `prv_test.fmt'; will try `prv_test.fmt'.

kpathsea: Running mktexfmt prv_test.fmt
mktexfmt: mktexfmt is using the following fmtutil.cnf files (in precedence order):
mktexfmt:   /etc/texmf/web2c/fmtutil.cnf
mktexfmt: mktexfmt is using the following fmtutil.cnf file for writing changes:
mktexfmt:   /home/berber/.texlive/texmf-config/web2c/fmtutil.cnf
mktexfmt [INFO]: writing formats under /home/berber/.texlive/texmf-var/web2c
mktexfmt [INFO]: did not find entry for byfmt=prv_test, skipped
mktexfmt [INFO]: Disabled formats: 6
mktexfmt [INFO]: Not selected formats: 36
mktexfmt [INFO]: Total formats: 42
mktexfmt [INFO]: exiting with status 0
I can't find the format file `prv_test.fmt'!

TeX Output exited as expected with code 1 at Mon Jun  3 16:17:28
LaTeX: LaTeX found no preview images