Civet generates the expected output. The output you're seeing is a bug in Prettier. Possibly fixed in a newer version; I'll check whether updating fixes it.

So it is. I'll try to remember to turn off Prettier in the playground next time I have a bug report.

Here's a relevant Prettier issue: prettier/prettier#16167
(also links to a discussion about the cause)

It turns out that wrapping the example in a function* (so that yield is valid) works:

function* f
  yield [2,3]
  yield await [foo, bar]

Playground link

It's plausible to me that we could fix this in some way, when there's a top-level yield like this.

• Perhaps we shouldn't run Prettier? (easiest)
• Perhaps we should try to wrap in function*, run Prettier, then unwrap? (the unwrapping seems tricky)

Or we could wait for Prettier to fix the bug (but it's been several months, so I wouldn't hold my breath).