Repro is with Brim commit cccb040.

A community zync user inquired:

Is there a way to use const <id> = <expr> in Zui?

Of course, Zui is intended to handle any valid syntax, but indeed there's a UX challenge here. The app tries to be helpful by populating a from pin when the user clicks Query Pool, which allows them to start writing searches and aggregations right in the editor. However, if they try to kick off their Zed with something like const, they get a syntax error.

If they're hip to what's going on and delete the from pin and put the from in the typed Zed after the const, now it starts to work.

It seems that whatever we might do to address this could also relate to #2533.