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

$ go version
go version go1.20.3 linux/amd64

Does this issue reproduce with the latest release?

Yes

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

$ go env
GO111MODULE="auto"
GOARCH="amd64"
GOBIN=""
GOCACHE="/home/vogtp/.cache/go-build"
GOENV="/home/vogtp/.config/go/env"
GOEXE=""
GOEXPERIMENT=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOINSECURE=""
GOMODCACHE="/home/vogtp/go/pkg/mod"
GONOPROXY=""
GONOSUMDB=""
GOOS="linux"
GOPATH="/home/vogtp/go/"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/home/vogtp/sdk/go1.20.3"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/home/vogtp/sdk/go1.20.3/pkg/tool/linux_amd64"
GOVCS=""
GOVERSION="go1.20.3"
GCCGO="gccgo"
GOAMD64="v1"
AR="ar"
CC="gcc"
CXX="g++"
CGO_ENABLED="1"
GOMOD="/home/vogtp/go/src/github.com/vogtp/slog-tests/go.mod"
GOWORK=""
CGO_CFLAGS="-O2 -g"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-O2 -g"
CGO_FFLAGS="-O2 -g"
CGO_LDFLAGS="-O2 -g"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -Wl,--no-gc-sections -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build1680678466=/tmp/go-build -gno-record-gcc-switches"

What did you do?

Create a new slog with attributes:

https://go.dev/play/p/G9K0STO5xVT

What did you expect to see?

A "copy" of slog

What did you see instead?

panic: bad kind: 9

goroutine 1 [running]:
golang.org/x/exp/slog.appendJSONValue(0xc00009ae48, {0x4c0ae0?, {0x4c0ae0?, 0x5b59c8?}})
/tmp/gopath3992858384/pkg/mod/golang.org/x/exp@v0.0.0-20230419192730-864b3d6c5c2c/slog/json_handler.go:145 +0x774
golang.org/x/exp/slog.(*handleState).appendValue(0xc00009ae48, {0x4d1da2?, {0x4c0ae0?, 0x5b59c8?}})
/tmp/gopath3992858384/pkg/mod/golang.org/x/exp@v0.0.0-20230419192730-864b3d6c5c2c/slog/handler.go:540 +0x30
golang.org/x/exp/slog.(*handleState).appendAttr(0xc00009ae48, {{0x4d1da2, 0x1}, {0x0, {0x4c0ae0, 0x5b59c8}}})
/tmp/gopath3992858384/pkg/mod/golang.org/x/exp@v0.0.0-20230419192730-864b3d6c5c2c/slog/handler.go:478 +0x6e5
golang.org/x/exp/slog.(*commonHandler).withAttrs(0xc00007a090, {0xc000016120, 0x1, 0x4bb880?})
/tmp/gopath3992858384/pkg/mod/golang.org/x/exp@v0.0.0-20230419192730-864b3d6c5c2c/slog/handler.go:237 +0x4e5
golang.org/x/exp/slog.(*JSONHandler).WithAttrs(0x4c0ae0?, {0xc000016120?, 0xc000094000?, 0x0?})
/tmp/gopath3992858384/pkg/mod/golang.org/x/exp@v0.0.0-20230419192730-864b3d6c5c2c/slog/json_handler.go:54 +0x25
main.main()
/tmp/sandbox1421477762/prog.go:11 +0x15f