What version of Go are you using (go version)?

go version go1.19rc2 darwin/amd64

Does this issue reproduce with the latest release?

Yes

What operating system and processor architecture are you using (go env)?

GOARCH="amd64"
GOOS="darwin"

What did you do?

Using the slog package, ran the following program, as well as one with NewTextHandler

func main() {
	log := slog.New( slog.NewJSONHandler(os.Stdout)).With("job", "Eulerian Gophers" )
	log = log.With( "id", 1 )
	log.Log( slog.InfoLevel, "", "total", 5050 )
}

func main() {
	scully := slog.New( slog.NewTextHandler(os.Stdout))
	scully.Error( "👩‍🦰", errors.New("🛸"))
}

What did you expect to see?

For the first program, JSON parseable by gojq

For the second program, a log message showing some error associating Agent Scully and a UFO

(I don't have the expectation that slog is anything but /x/exp, but just noticed these things)

What did you see instead?

For the first program:

"level":"INFO","msg":"","job":"Eulerian Gophers""id":1,"total":5050}

this isn't parsed because there should be a [edit] a comma here: "Eulerian Gophers","id". There is a similar glitch with TextHandler output, and I guess it's the preformatting. With("job", "Eulerian Gophers", "id", 1 ) eliminates the glitch.

For the second program, using

level=ERROR msg="👩\u200d🦰" err=🛸

Using JSON seems to avoid escaping the zero width joiner.

[edit: fixed a few details in description that were backwards]