fix graceful shutdown

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

kgo.go

@@ -11,13 +11,14 @@ import (
 	"time"
 
 	"github.com/twmb/franz-go/pkg/kgo"
+	"github.com/twmb/franz-go/pkg/kmsg"
 	"go.unistack.org/micro/v3/broker"
 	"go.unistack.org/micro/v3/metadata"
 	id "go.unistack.org/micro/v3/util/id"
 	mrand "go.unistack.org/micro/v3/util/rand"
 )
 
-var _ broker.Broker = &Broker{}
+var _ broker.Broker = (*Broker)(nil)
 
 var ErrLostMessage = errors.New("message not marked for offsets commit and will be lost in next iteration")
 
@@ -134,6 +135,9 @@ func (k *Broker) Disconnect(ctx context.Context) error {
 		return nctx.Err()
 	default:
 		for _, sub := range k.subs {
+			if sub.closed {
+				continue
+			}
 			if err := sub.Unsubscribe(ctx); err != nil {
 				return err
 			}
@@ -306,6 +310,18 @@ func (k *Broker) Subscribe(ctx context.Context, topic string, handler broker.Han
 		return nil, err
 	}
 
+	mdreq := kmsg.NewMetadataRequest()
+	mdreq.Topics = []kmsg.MetadataRequestTopic{
+		{Topic: &topic},
+	}
+
+	mdrsp, err := mdreq.RequestWith(ctx, c)
+	if err != nil {
+		return nil, err
+	} else if mdrsp.Topics[0].ErrorCode != 0 {
+		return nil, fmt.Errorf("topic %s not exists or permission error", topic)
+	}
+
 	sub.c = c
 	go sub.poll(ctx)