server.go: prevent partial mutation of currNodeAnn

In this commit, we prevent partial mutation of current
node announcement during announcement signing. If node
announcement signing failed the current node announcement
becomes inconsistent.

server.go

@@ -3432,6 +3432,11 @@ func (s *server) genNodeAnnouncement(features *lnwire.RawFeatureVector,
 	s.mu.Lock()
 	defer s.mu.Unlock()
 
+	// Create a shallow copy of the current node announcement to work on.
+	// This ensures the original announcement remains unchanged
+	// until the new announcement is fully signed and valid.
+	newNodeAnn := *s.currentNodeAnn
+
 	// First, try to update our feature manager with the updated set of
 	// features.
 	if features != nil {
@@ -3457,17 +3462,20 @@ func (s *server) genNodeAnnouncement(features *lnwire.RawFeatureVector,
 
 	// Apply the requested changes to the node announcement.
 	for _, modifier := range modifiers {
-		modifier(s.currentNodeAnn)
+		modifier(&newNodeAnn)
 	}
 
 	// Sign a new update after applying all of the passed modifiers.
 	err := netann.SignNodeAnnouncement(
-		s.nodeSigner, s.identityKeyLoc, s.currentNodeAnn,
+		s.nodeSigner, s.identityKeyLoc, &newNodeAnn,
 	)
 	if err != nil {
 		return lnwire.NodeAnnouncement{}, err
 	}
 
+	// If signing succeeds, update the current announcement.
+	*s.currentNodeAnn = newNodeAnn
+
 	return *s.currentNodeAnn, nil
 }