Some changes to logging and NPE handling.

Mage.Server/src/main/java/mage/server/ChatSession.java

@@ -72,10 +72,14 @@ public class ChatSession {
     public void  kill(UUID userId, DisconnectReason reason) {
 
         try {
-            if (userId != null && clients.containsKey(userId)) {
+            if (reason == null) {
+                logger.fatal("User kill without disconnect reason  userId: " + userId) ;
+                reason = DisconnectReason.Undefined;
+            }
+            if (reason != null && userId != null && clients.containsKey(userId)) {
                 String userName = clients.get(userId);
                 clients.remove(userId);
-                logger.debug(userName + (reason == null?"null":"(" + reason.toString() +")") + " removed from chatId " + chatId) ;
+                logger.debug(userName + "(" + reason.toString() +")" + " removed from chatId " + chatId) ;
                 String message;
                 switch (reason) {
                     case Disconnected:
@@ -85,7 +89,7 @@ public class ChatSession {
                         message = " has lost connection";
                         break;
                      default:
-                        message = reason == null ? " left (unknown reason) ": " left (" + reason.toString() +")";
+                        message = " left (" + reason.toString() +")";
                 }
                 if (message != null) {
                     broadcast(null, new StringBuilder(userName).append(message).toString(), MessageColor.BLUE, true, MessageType.STATUS);

Mage.Server/src/main/java/mage/server/TableController.java

@@ -510,8 +510,11 @@ public class TableController {
                         }
                     }
                     else {
-                        logger.error("Unable to find player " + entry.getKey());
+                        logger.error("Unable to find user: " + entry.getKey() + "  playerId: " + entry.getValue());
-                        match.getPlayer(entry.getValue()).setQuit(true);
+                        MatchPlayer matchPlayer = match.getPlayer(entry.getValue());
+                        if (matchPlayer != null && !matchPlayer.hasQuit()) {
+                            matchPlayer.setQuit(true);
+                        }
                     }
                 }
             }
@@ -526,11 +529,16 @@ public class TableController {
             }
             ServerMessagesUtil.getInstance().incGamesStarted();
 
+
             // log about game started
             logger.info("GAME started [" + match.getName() +"] "+ creator + " - " + opponent.toString());
             logger.debug("- matchId: " + match.getId() + " [" + match.getName() + "]");
+            if (match.getGame() != null) {
                 logger.debug("- gameId:  " + match.getGame().getId());
                 logger.debug("- chatId:  " + GameManager.getInstance().getChatId(match.getGame().getId()));
+            } else {
+                logger.debug("- no valid game object");
+            }
             LogServiceImpl.instance.log(LogKeys.KEY_GAME_STARTED, String.valueOf(userPlayerMap.size()), creator, opponent.toString());
         }
         catch (Exception ex) {
@@ -622,6 +630,9 @@ public class TableController {
      */
     public boolean endGameAndStartNextGame() {
         // get player that chooses who goes first
+        if (match.getGame() == null) {
+            return true;
+        }
         UUID choosingPlayerId = match.getChooser();
         match.endGame();
         if (ConfigSettings.getInstance().isSaveGameActivated() && !match.getGame().isSimulation()) {

Mage.Server/src/main/java/mage/server/UserManager.java

@@ -81,8 +81,11 @@ public class UserManager {
     }
 
     public User getUser(UUID userId) {
+        if (userId != null) {
             return users.get(userId);
         }
+        return null;
+    }
 
     public User findUser(String userName) {
         for (User user: users.values()) {

Mage.Sets/src/mage/sets/theros/XenagosTheReveler.java

@@ -117,26 +117,32 @@ class XenagosManaEffect extends OneShotEffect {
     @Override
     public boolean apply(Game game, Ability source) {
         Player player = game.getPlayer(source.getControllerId());
-        if(player != null){
+        if (player != null){
             int x = game.getBattlefield().count(new FilterControlledCreaturePermanent(), source.getSourceId(), source.getControllerId(), game);
             Choice manaChoice = new ChoiceImpl();
-            Set<String> choices = new LinkedHashSet<String>();
+            Set<String> choices = new LinkedHashSet<>();
             choices.add("Red");
             choices.add("Green");
             manaChoice.setChoices(choices);
             manaChoice.setMessage("Select color of mana to add");
 
-            for(int i = 0; i < x; i++){
+            for (int i = 0; i < x; i++){
                 Mana mana = new Mana();
                 while (!player.choose(Outcome.Benefit, manaChoice, game)) {
                     if (!player.isInGame()) {
                         return false;
                     }
                 }
-                if (manaChoice.getChoice().equals("Green")) {
+                if (manaChoice.getChoice() == null) {  // can happen if player leaves game
+                    return false;
+                }
+                switch (manaChoice.getChoice()) {
+                    case "Green":
                         mana.addGreen();
-                } else if (manaChoice.getChoice().equals("Red")) {
+                        break;
+                    case "Red":
                         mana.addRed();
+                        break;
                 }
                 player.getManaPool().addMana(mana, game, source);
             }

Mage.Tests/src/test/java/org/mage/test/cards/abilities/keywords/PersistTest.java

@@ -158,7 +158,7 @@ public class PersistTest extends CardTestPlayerBase {
         assertPowerToughness(playerA, "Kitchen Finks", 3,2, Filter.ComparisonScope.Any);
 
         assertLife(playerA, 20); // No life from Kitchen Finks ETB becaus of Torpor Orb
-        assertLife(playerB, 22); // AI assigns damage only 2 damage to one blocker so only 2 life link (It's a kind of bug (or bad play) of AI)
+        assertLife(playerB, 22); // AI assigns only 2 damage to one blocker so only 2 life link (It's a kind of bug (or bad play) of AI)
 
     }
 

Mage/src/mage/abilities/effects/ContinuousEffects.java

@@ -865,6 +865,9 @@ public class ContinuousEffects implements Serializable {
     }
 
     public void addEffect(ContinuousEffect effect, Ability source) {
+        if (source == null && effect != null) {
+            logger.warn("Adding effect without ability : " +effect.toString());
+        }
         switch (effect.getEffectType()) {
             case REPLACEMENT:
             case REDIRECTION:

Mage/src/mage/game/GameImpl.java

@@ -934,7 +934,7 @@ public abstract class GameImpl implements Game, Serializable {
     public void quit(UUID playerId) {
         if (state != null) {
             Player player = state.getPlayer(playerId);
-            if (player != null) {
+            if (player != null && player.isInGame()) {
                 player.quit(this);
             }
         }