Fix NPEs relating combat checks and world changing. Fixes #976, #979

src/main/java/com/gmail/nossr50/listeners/PlayerListener.java

@@ -128,6 +128,10 @@ public class PlayerListener implements Listener {
 
         McMMOPlayer mcMMOPlayer = UserManager.getPlayer(player);
 
+        if (mcMMOPlayer == null) {
+            return;
+        }
+
         if (mcMMOPlayer.getGodMode() && !Permissions.mcgod(player)) {
             mcMMOPlayer.toggleGodMode();
             player.sendMessage(LocaleLoader.getString("Commands.GodMode.Forbidden"));

src/main/java/com/gmail/nossr50/runnables/commands/MctopCommandAsyncTask.java

@@ -29,5 +29,4 @@ public class MctopCommandAsyncTask extends BukkitRunnable {
 
         new MctopCommandDisplayTask(userslist, page, tablePrefix, sender).runTaskLater(mcMMO.p, 1);
     }
-
 }

src/main/java/com/gmail/nossr50/util/skills/CombatUtils.java

@@ -266,7 +266,7 @@ public final class CombatUtils {
         if (target instanceof Player) {
             Player player = (Player) target;
 
-            if (Misc.isNPCEntity(player)) {
+            if (Misc.isNPCEntity(player) || !player.isOnline()) {
                 return;
             }
 
@@ -291,6 +291,11 @@ public final class CombatUtils {
         }
         else if (attacker instanceof Player) {
             Player player = (Player) attacker;
+
+            if (Misc.isNPCEntity(player)) {
+                return;
+            }
+
             PlayerProfile profile = UserManager.getPlayer(player).getProfile();
 
             if (Permissions.mobHealthDisplay(player) && profile.getMobHealthbarType() != MobHealthbarType.DISABLED) {