When tx is run (in my case via fontmake) and the TMPDIR environment variable is set to a path that does not exist, tx crashes.
Repro:
( TMPDIR=/does/not/exist ; \
fontmake -u RSMSIntra-Condensed.ufo -o otf --output-path out.otf \
--overlaps-backend pathops --production-names --optimize-cff 2 \
--verbose DEBUG
Full log here: https://gist.github.com/rsms/e9946c7f28bb6e663b622e9c4b7f16f0
tx seem to write data and then read it back in again. I wonder if it can skip that disk write-and-read middle step?