I get an error every time I run `op`.

when I echo'd $TMPDIR, I got back an entirely different directory:
/var/folders/rr/4p_t05vx7q16xls8nsyx7hlh0000gn/T/
(I imagine that the subdirectory of /var/folders/rr changes name with each session?)

I did a bit more troubleshooting and decided to run rg. And lo, it would appear that $XDG_RUNTIME_DIR was actually set by a script then subsequently unset once another script had finished running. (Don't ask.) In the interim, op would get called.

So, I fixed that.

Now it works.

User error..

You devs? Did a great job. No debugging required, no hunting down. etc...

Mea culpa.

Have a great day!