Set `setChooseAvatarGuid` properly

src/main/java/emu/grasscutter/game/player/Player.java

@@ -642,6 +642,9 @@ public class Player {
     }
 
     public void setMainCharacterId(int mainCharacterId) {
+        if (this.mainCharacterId != 0) {
+            return;
+        }
         this.mainCharacterId = mainCharacterId;
     }
 

src/main/java/emu/grasscutter/server/packet/send/PacketAvatarDataNotify.java

@@ -13,11 +13,11 @@ import emu.grasscutter.net.proto.AvatarTeamOuterClass.AvatarTeam;
 public class PacketAvatarDataNotify extends BasePacket {
 	
 	public PacketAvatarDataNotify(Player player) {
-		super(PacketOpcodes.AvatarDataNotify, 2);
+		super(PacketOpcodes.AvatarDataNotify, true);
 		
 		AvatarDataNotify.Builder proto = AvatarDataNotify.newBuilder()
 				.setCurAvatarTeamId(player.getTeamManager().getCurrentTeamId())
-				.setChooseAvatarGuid(player.getTeamManager().getCurrentCharacterGuid())
+				//.setChooseAvatarGuid(player.getTeamManager().getCurrentCharacterGuid())
 				.addAllOwnedFlycloakList(player.getFlyCloakList())
 				.addAllOwnedCostumeList(player.getCostumeList());
 				
@@ -38,6 +38,12 @@ public class PacketAvatarDataNotify extends BasePacket {
 			proto.putAvatarTeamMap(entry.getKey(), avatarTeam.build());
 		}
 		
+		// Set main character
+		Avatar mainCharacter = player.getAvatars().getAvatarById(player.getMainCharacterId());
+		if (mainCharacter != null) {
+		    proto.setChooseAvatarGuid(mainCharacter.getGuid());
+		}
+		
 		this.setData(proto.build());
 	}