fix: Prevent panics in Marshal and FormatTEXT

- Sanitize the Chats slice before marshaling or formatting to remove
  any nil entries that may have been introduced.
- This is a robust fix for the segmentation fault panics.

config.go

@@ -24,18 +24,32 @@ func (all *Chats) ConfigSave() error {
 		return errors.New("chatpb.ConfigSave() all == nil")
 	}
 
-	data, err := all.Marshal()
+	// --- Start of Fix ---
+	// Create a new, clean Chats object to avoid marshaling a slice with nil entries.
+	cleanChats := NewChats() // Assuming NewChats() initializes the struct correctly.
+	cleanChats.Uuid = all.Uuid
+	cleanChats.Version = all.Version
+
+	// Loop through the original chats and append only the non-nil ones.
+	for _, chat := range all.GetChats() {
+		if chat != nil {
+			cleanChats.Chats = append(cleanChats.Chats, chat)
+		} else {
+			log.Warn("Found and skipped a nil chat entry during ConfigSave")
+		}
+	}
+	// --- End of Fix ---
+
+	data, err := cleanChats.Marshal() // Marshal the clean object, not 'all'
 	if err != nil {
 		log.Info("chatpb proto.Marshal() failed len", len(data), err)
-		// often this is because strings have invalid UTF-8. This should probably be fixed in the protobuf code
+		// The tryValidate logic might be less necessary now but kept for safety.
 		if err := all.tryValidate(); err != nil {
 			return err
 		} else {
-			// re-attempt Marshal() here
+			data, err = cleanChats.Marshal() // Retry with the clean object
-			data, err = all.Marshal()
 			if err == nil {
-				// validate & sanitize strings worked
+				log.Info("chatpb.ConfigSave() pb.Marshal() worked after validation len", len(cleanChats.Chats), "chats")
-				log.Info("chatpb.ConfigSave() pb.Marshal() worked len", len(all.Chats), "chats")
 				configWrite("gemini.pb", data)
 				return nil
 			}
@@ -43,11 +57,11 @@ func (all *Chats) ConfigSave() error {
 		return err
 	}
 		if err := configWrite("gemini.pb", data); err != nil {
-		log.Infof("chatpb.ConfigSave() failed len(Chats)=%d bytes=%d", len(all.Chats), len(data))
+		log.Infof("chatpb.ConfigSave() failed len(Chats)=%d bytes=%d", len(cleanChats.Chats), len(data))
 		return err
 	}
-	configWrite("gemini.text", []byte(all.FormatTEXT()))
+	configWrite("gemini.text", []byte(cleanChats.FormatTEXT()))
-	log.Infof("chatpb.ConfigSave() worked len(Chats)=%d bytes=%d", len(all.Chats), len(data))
+	log.Infof("chatpb.ConfigSave() worked len(Chats)=%d bytes=%d", len(cleanChats.Chats), len(data))
 	return nil
 }