Just got a comment about this error. If I run my plugin from “Run > Published Version” in the Development list, it runs fine. If I run it from the Plugins menu I see the error.
Elaborating on this – Right before this error started occurring for me, my Figma file was not allowing me to select the frame and open a plugin on it (no errors, just wouldn’t select when clicking). I right-clicked the tab and hit “Refresh Tab” and then noticed there were two instances of my account on the file (Almost like we were collaborating)… I then closed and re-opened Figma, and BOOM! The error started happening.
The issue has been resolved! Saved plugins are now running as expected from menus and quick-actions. Please let us know if you run into any further issues.