NetworkDispatcher exception io.netty.handler.codec.EncoderException: java.lang.NullPointerException

[vladmany]

I need to trigger a player's attack action.
I copied the net.minecraft.client.Minecraft.clickMouse() method from the sources and changed it a bit, removing everything about the leftClickCounter private property:
 

public static void callAttackAction() {
        Minecraft instance = Minecraft.getMinecraft();
        if (!instance.player.isRowingBoat())
        {
            switch (instance.objectMouseOver.typeOfHit)
            {
                case ENTITY:
                    if (instance.objectMouseOver.entityHit != null && instance.playerController != null) {
                        try {
                            instance.playerController.attackEntity(instance.player, instance.objectMouseOver.entityHit);
                        } catch (Exception e) {
                            e.printStackTrace();
                        }

                    }
                    break;
                case BLOCK:
                    BlockPos blockpos = instance.objectMouseOver.getBlockPos();

                    if (!instance.world.isAirBlock(blockpos))
                    {
                        instance.playerController.clickBlock(blockpos, instance.objectMouseOver.sideHit);
                        break;
                    }

                case MISS:
                    instance.player.resetCooldown();
                    net.minecraftforge.common.ForgeHooks.onEmptyLeftClick(instance.player);
            }

            instance.player.swingArm(EnumHand.MAIN_HAND);
        }
    }

It works, but sometimes times this error occurs on line 168 in the attackEntity method:
[Netty Client IO #1/ERROR] [FML]: NetworkDispatcher exception
io.netty.handler.codec.EncoderException: java.lang.NullPointerException
at io.netty.handler.codec.MessageToByteEncoder.write(MessageToByteEncoder.java:125) ~[MessageToByteEncoder.class:4.1.9.Final]
at io.netty.channel.AbstractChannelHandlerContext.invokeWrite0(AbstractChannelHandlerContext.java:738) ~[AbstractChannelHandlerContext.class:4.1.9.Final]
at io.netty.channel.AbstractChannelHandlerContext.invokeWrite(AbstractChannelHandlerContext.java:730) ~[AbstractChannelHandlerContext.class:4.1.9.Final]
at io.netty.channel.AbstractChannelHandlerContext.write(AbstractChannelHandlerContext.java:816) ~[AbstractChannelHandlerContext.class:4.1.9.Final]
at io.netty.channel.AbstractChannelHandlerContext.write(AbstractChannelHandlerContext.java:723) ~[AbstractChannelHandlerContext.class:4.1.9.Final]
at net.minecraftforge.fml.common.network.handshake.NetworkDispatcher.write(NetworkDispatcher.java:548) ~[NetworkDispatcher.class:?]
at io.netty.channel.AbstractChannelHandlerContext.invokeWrite0(AbstractChannelHandlerContext.java:738) ~[AbstractChannelHandlerContext.class:4.1.9.Final]
at io.netty.channel.AbstractChannelHandlerContext.invokeWriteAndFlush(AbstractChannelHandlerContext.java:801) ~[AbstractChannelHandlerContext.class:4.1.9.Final]
at io.netty.channel.AbstractChannelHandlerContext.write(AbstractChannelHandlerContext.java:814) ~[AbstractChannelHandlerContext.class:4.1.9.Final]
at io.netty.channel.AbstractChannelHandlerContext.writeAndFlush(AbstractChannelHandlerContext.java:794) ~[AbstractChannelHandlerContext.class:4.1.9.Final]
at io.netty.channel.AbstractChannelHandlerContext.writeAndFlush(AbstractChannelHandlerContext.java:831) ~[AbstractChannelHandlerContext.class:4.1.9.Final]
at io.netty.channel.DefaultChannelPipeline.writeAndFlush(DefaultChannelPipeline.java:1032) ~[DefaultChannelPipeline.class:4.1.9.Final]
at io.netty.channel.AbstractChannel.writeAndFlush(AbstractChannel.java:296) ~[AbstractChannel.class:4.1.9.Final]
at net.minecraft.network.NetworkManager$4.run(NetworkManager.java:245) [NetworkManager$4.class:?]
at io.netty.util.concurrent.AbstractEventExecutor.safeExecute(AbstractEventExecutor.java:163) [AbstractEventExecutor.class:4.1.9.Final]
at io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(SingleThreadEventExecutor.java:403) [SingleThreadEventExecutor.class:4.1.9.Final]
at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:442) [NioEventLoop.class:4.1.9.Final]
at io.netty.util.concurrent.SingleThreadEventExecutor$5.run(SingleThreadEventExecutor.java:858) [SingleThreadEventExecutor$5.class:4.1.9.Final]
at java.lang.Thread.run(Thread.java:748) [?:1.8.0_281]
Caused by: java.lang.NullPointerException
at net.minecraft.network.play.client.CPacketPlayerDigging.writePacketData(CPacketPlayerDigging.java:41) ~[CPacketPlayerDigging.class:?]
at net.minecraft.network.NettyPacketEncoder.encode(NettyPacketEncoder.java:51) ~[NettyPacketEncoder.class:?]
at net.minecraft.network.NettyPacketEncoder.encode(NettyPacketEncoder.java:12) ~[NettyPacketEncoder.class:?]
at io.netty.handler.codec.MessageToByteEncoder.write(MessageToByteEncoder.java:107) ~[MessageToByteEncoder.class:4.1.9.Final]

How can I fix it?

[DaemonUmbra]

Why do you need to trigger the attack action?

[vladmany]

  On 5/17/2021 at 4:54 AM, DaemonUmbra said:

Why do you need to trigger the attack action?

Expand  

I am creating a modification for one RPG server, which should, when holding down a certain key, continuously force the player to attack, like he would press the left mouse button many times. This is not a cheat! Clickers are allowed on this server. Only I want to trigger the attack itself, and not a click of the left mouse button. Sorry for my English.