Hi Jameson,
I figured it out! First I recreated the same exact environment as you,
and I still didn't see the error. Then I realized that GNU Radio was
getting the `newmod_path` for the template from ~/.gnuradio/config.conf,
and mine was pointing to a newer installation. (That's something that
own its own needs a fix, in my view.) Once I got it pointing to the
actual GR 3.8.2 installation, then I saw the same error.
That let me track it down to essentially the same problem as
https://github.com/gnuradio/gnuradio/issues/5068, which is that the
template as installed by conda was including __pycache__ .pyc files, and
those were causing the exception. I fixed that particular issue with the
conda packaging before releasing GR 3.8.3.1. Can you use a newer version
of GR 3.8? If you just change your installation to `conda install
gnuradio=3.8`, you should get a version of modtool that works. Either
that or go to
/home/jcollins/Downloads/temp/deleteme/envs/asdf/lib/python3.9/site-packages/gnuradio/modtool/templates/
and delete the __pycache__ folder.