cue fmt adds two newlines instead of one to an empty file

[DenisGorbachev]

What version of CUE are you using (cue version)?

cue version v0.12.1

go version go1.24.2
      -buildmode exe
       -compiler gc
       -trimpath true
     CGO_ENABLED 0
          GOARCH arm64
            GOOS darwin
         GOARM64 v8.0
cue.lang.version v0.12.0

Does this issue reproduce with the latest stable release?

Yes

What did you do?

cd $(mktemp -d)
(
set -e
touch example.cue
cue fmt example.cue
cat example.cue
)

What did you expect to see?

One newline.

What did you see instead?

Two newlines.