logger/slog: write stacktrace on error if enabled, and always on fatal

Signed-off-by: Vasiliy Tolstov <v.tolstov@unistack.org>

logger/slog/slog.go

@@ -270,7 +270,7 @@ func (s *slogLogger) printLog(ctx context.Context, lvl logger.Level, msg string,
 		}
 	}
 
-	if s.opts.AddStacktrace && lvl == logger.ErrorLevel {
+	if (s.opts.AddStacktrace || lvl == logger.FatalLevel) || (s.opts.AddStacktrace && lvl == logger.ErrorLevel) {
 		stackInfo := make([]byte, 1024*1024)
 		if stackSize := runtime.Stack(stackInfo, false); stackSize > 0 {
 			traceLines := reTrace.Split(string(stackInfo[:stackSize]), -1)

logger/slog/slog_test.go

@@ -15,6 +15,24 @@ import (
 	"go.unistack.org/micro/v3/metadata"
 )
 
+func TestStacktrace(t *testing.T) {
+	ctx := context.TODO()
+	buf := bytes.NewBuffer(nil)
+	l := NewLogger(logger.WithLevel(logger.ErrorLevel), logger.WithOutput(buf),
+		WithHandlerFunc(slog.NewTextHandler),
+		logger.WithAddStacktrace(true),
+	)
+	if err := l.Init(logger.WithFields("key1", "val1")); err != nil {
+		t.Fatal(err)
+	}
+
+	l.Error(ctx, "msg1", errors.New("err"))
+
+	if !bytes.Contains(buf.Bytes(), []byte(`slog_test.go:29`)) {
+		t.Fatalf("logger error not works, buf contains: %s", buf.Bytes())
+	}
+}
+
 func TestWithFields(t *testing.T) {
 	ctx := context.TODO()
 	buf := bytes.NewBuffer(nil)