Hotfix scoreboard

SpigotCore_Main/src/de/steamwar/scoreboard/SWScoreboard.java

@@ -62,6 +62,8 @@ public class SWScoreboard {
                     throw new SecurityException("Could not send scoreboard packets", e);
                 }
                 Bukkit.getScheduler().runTaskLater(Core.getInstance(), () -> {
+                    if(!player.isOnline())
+                        return;
                     try {
                         ProtocolLibrary.getProtocolManager().sendServerPacket(player, DISPLAY_SIDEBAR[toggle]);
                     } catch (InvocationTargetException e) {