Fix send duplicate message in trace interceptor (#709)

diff --git a/producer/interceptor.go b/producer/interceptor.go
index b3d2598..160deac 100644
--- a/producer/interceptor.go
+++ b/producer/interceptor.go
@@ -50,7 +50,7 @@
 
 		producerCtx := primitive.GetProducerCtx(ctx)
 		if producerCtx.Message.Topic == dispatcher.GetTraceTopicName() {
-			return next(ctx, req, reply)
+			return err
 		}
 
 		// SendOneway && SendAsync has no reply.