pmos.log stops at pmos_install, but output from TWRP install continues

Attempting to install postmarketOS v24.06 on samsung-degaswifi using adb push + TWRP-3.7.0_9-0 install.

TWRP install output stops at Formatting root partition... Failed.

pmos.log stops at + chroot /tmp/postmarketos/chroot /bin/pmos_install

The pmos_chroot script has:

exec > /tmp/postmarketos/pmos.log 2>&1
set -ex

and pmos_install has:

exec >> /pmos.log 2>&1
set -ex

Editing the pmos_install script to match pmos_chroot gives the following error:

/bin/pmos_install: line 21: can't create /tmp/postmarketos/pmos.log: nonexistent directory

I'm trying to figure out pmaports#2170, which is running into an error in pmos_install, but this is making that difficult.