Ensure that the player is online.

src/main/java/us/myles/ViaVersion/protocols/protocol1_9to1_8/ViaIdleThread.java

@@ -70,6 +70,7 @@ public class ViaIdleThread extends BukkitRunnable {
             }
         }
     }
+
     @Override
     public void run() {
         for (UserConnection info : portedPlayers.values()) {
@@ -79,16 +80,20 @@ public class ViaIdleThread extends BukkitRunnable {
                     if (info.getChannel().isOpen()) {
                         if (USE_NMS) {
                             Player player = Bukkit.getPlayer(info.get(ProtocolInfo.class).getUuid());
+                            if (player != null) {
                                 try {
                                     // Tick player
                                     Object entityPlayer = getHandle.invoke(player);
                                     Object pc = connection.get(entityPlayer);
+                                    if (pc != null) {
                                         handleFlying.invoke(pc, (info.get(MovementTracker.class).isGround() ? idlePacket2 : idlePacket));
                                         // Tick world
                                         info.get(MovementTracker.class).incrementIdlePacket();
+                                    }
                                 } catch (IllegalAccessException | InvocationTargetException e) {
                                     e.printStackTrace();
                                 }
+                            }
                         } else {
                             // Old method using packets.
                             ChannelHandlerContext context = PipelineUtil.getContextBefore("decoder", info.getChannel().pipeline());