The default tmpfs on my install seems to small to run the pkg command properly (this seems separately reported). When it reports an out-of-space error, it would be useful if it reported the pathname affected, not just the API that saw the error:
> root@generic:/home/robert/cambridge-l41-aos-labs/2020-2021/Laboratories/ipc # pkg install python
> Updating FreeBSD repository catalogue...
> Fetching meta.txz: 100% 916 B 0.9kB/s 00:01
> Fetching packagesite.txz: 100% 6 MiB 5.8MB/s 00:01
> pkg: archive_read_extract(extract error): No space left on device
> pkg: No signature found
> Unable to update repository FreeBSD
> Error updating repositories!
Above, it would be more immediately useful to the user if the pkg error had indicated that it was /tmp that was out of space.
(This is with pkg-1.15.10 on FreeBSD-CURRENT running on aarch64 on an RPi4.)