Player#isOnline is not thread safe

CraftBukkit 1.8.8 implementation checks whether Bukkit.getPlayer(<player
uuid>) != null. Bukkit.getPlayer(UUID) is itself not thread safe.

api/src/main/java/net/jitse/npclib/listeners/PlayerListener.java

@@ -64,7 +64,7 @@ public class PlayerListener extends HandleMoveBase implements Listener {
                         this.cancel();
                     }
                 }
-            }.runTaskTimerAsynchronously(instance.getPlugin(), 0, 1);
+            }.runTaskTimer(instance.getPlugin(), 0L, 1L);
         }
     }