GstLAL dev container doesn't allow writable

Following these instructions:

https://lscsoft.docs.ligo.org/gstlal/installation.html

on ICDS here:

/ligo/home/ligo.org/gstlalcbc/observing/4/chad/master_test_21_11_11

I did

$ singularity build --sandbox --fix-perms gstlal-dev docker://containers.ligo.org/lscsoft/gstlal:master
$ singularity run --writable gstlal-dev
WARNING: By using --writable, Singularity can't create /ligo destination automatically without overlay or underlay
FATAL:   container creation failed: mount /var/singularity/mnt/session/ligo->/ligo error: while mounting /var/singularity/mnt/session/ligo: destination /ligo doesn't exist in container

What can I do now?