How do i fix this 

https://prnt.sc/12ndzkx

no it just parties all the players ingame

package com.example.examplemod;

import java.util.Collection;

import net.minecraft.client.Minecraft;
import net.minecraft.client.network.NetworkPlayerInfo;
import net.minecraft.command.CommandBase;
import net.minecraft.command.CommandException;
import net.minecraft.command.ICommand;
import net.minecraft.command.ICommandSender;
import net.minecraftforge.client.ClientCommandHandler;
import net.minecraftforge.common.MinecraftForge;
import net.minecraftforge.fml.common.Mod;
import net.minecraftforge.fml.common.Mod.EventHandler;
import net.minecraftforge.fml.common.event.FMLPostInitializationEvent;

@Mod(modid = "PartyAll", name = "PartyAll", version = "1.0", acceptedMinecraftVersions = "[1.8.9]")
public class ExampleMod
  extends CommandBase
{
  @EventHandler
  public void init(FMLPostInitializationEvent event) {
    MinecraftForge.EVENT_BUS.register(this);
    
    ClientCommandHandler.instance.func_71560_a((ICommand)this);
  }

  public int func_82362_a() {
    return 0;
  }

  
  public String func_71517_b() {
    return "pall";
  }

  
  public String func_71518_a(ICommandSender sender) {
    return null;
  }

  
  public void func_71515_b(ICommandSender sender, String[] args) throws CommandException {
    (new Thread(() -> myRun(sender))).start();
  }
  public void myRun(ICommandSender sender) {
    Collection<NetworkPlayerInfo> playersC = Minecraft.func_71410_x().func_147114_u().func_175106_d();
    playersC.forEach(loadedPlayer -> {
          String loadedPlayerName = loadedPlayer.func_178845_a().getName();
          (Minecraft.func_71410_x()).field_71439_g.func_71165_d("/p invite " + loadedPlayerName);
          try { 
            Thread.sleep(150L);
          } catch (InterruptedException e) {
            e.printStackTrace();
          } 
        });
  }

@Override
public String getCommandName() {
    // TODO Auto-generated method stub
    return null;
}

@Override
public String getCommandUsage(ICommandSender sender) {
    // TODO Auto-generated method stub
    return null;
}

@Override
public void processCommand(ICommandSender sender, String[] args) throws CommandException {
    // TODO Auto-generated method stub
    
}
}

"That is my whole code"

1.8 is no longer supported on this forum.
Please update to a modern version of Minecraft to receive support.