Fix tower defense first clear rewards

src/main/java/emu/nebula/server/handlers/HandlerActivityTowerDefenseLevelSettleReq.java

@@ -22,17 +22,20 @@ public class HandlerActivityTowerDefenseLevelSettleReq extends NetHandler {
             return session.encodeMsg(NetMsgId.activity_tower_defense_level_settle_failed_ack);
         }
 
+        // Only receive rewards if we havent completed the stage
+        if (!activity.getCompletedStages().containsKey(req.getLevelId())) {
             // Claim rewards
             var change = activity.claimReward(req.getLevelId());
             
-        // Update completed stages
+            // Update completed stages and save activity to the database
             activity.getCompletedStages().put(req.getLevelId(), req.getStar());
-
-        // Save changes
-        session.getPlayer().save();
+            activity.save();
             
             // Encode and send
             return session.encodeMsg(NetMsgId.activity_tower_defense_level_settle_succeed_ack, change.toProto());
+        } else {
+            return session.encodeMsg(NetMsgId.activity_tower_defense_level_settle_succeed_ack);
+        }
     }
 
 }