brontide: increase logging when processing gossip msgs

We add logging to we can draw conclusions how long the processing
of gossip message last and potentially see whether the syncer
buffer channel size is a bottleneck in processing.

discovery/gossiper.go

@@ -860,8 +860,6 @@ func (d *AuthenticatedGossiper) stop() {
 func (d *AuthenticatedGossiper) ProcessRemoteAnnouncement(ctx context.Context,
 	msg lnwire.Message, peer lnpeer.Peer) chan error {
 
-	log.Debugf("Processing remote msg %T from peer=%x", msg, peer.PubKey())
-
 	errChan := make(chan error, 1)
 
 	// For messages in the known set of channel series queries, we'll

peer/brontide.go

@@ -1995,9 +1995,32 @@ func newDiscMsgStream(p *Brontide) *msgStream {
 		// so that a parent context can be passed in here.
 		ctx := context.TODO()
 
-		// TODO(yy): `ProcessRemoteAnnouncement` returns an error chan
-		// and we need to process it.
-		p.cfg.AuthGossiper.ProcessRemoteAnnouncement(ctx, msg, p)
+		p.log.Debugf("Processing remote msg %T", msg)
+
+		errChan := p.cfg.AuthGossiper.ProcessRemoteAnnouncement(
+			ctx, msg, p,
+		)
+
+		// Start a goroutine to process the error channel for logging
+		// purposes.
+		//
+		// TODO(ziggie): Maybe use the error to potentially punish the
+		// peer depending on the error ?
+		go func() {
+			select {
+			case <-p.cg.Done():
+				return
+
+			case err := <-errChan:
+				if err != nil {
+					p.log.Warnf("Error processing remote "+
+						"msg %T: %v", msg,
+						err)
+				}
+			}
+
+			p.log.Debugf("Processed remote msg %T", msg)
+		}()
 	}
 
 	return newMsgStream(