Need a serious help!

Hello! So to get started, i want to make an ffa plugin... i made the code and all alright, but then it comes out with this: ( see the error ) If you saw it see here: sooo if i press add return statement it give a return false, ok, but when i test the plugin it says [FFA] You are not allowed to do this. But it don't tp me to the place i have set or gives me the items + i set only one permission for /setffa. Please help.

Code:

package me.angelopoulos;



import java.util.ArrayList;

import org.bukkit.Bukkit;
import org.bukkit.ChatColor;
import org.bukkit.Location;
import org.bukkit.Material;
import org.bukkit.World;
import org.bukkit.command.Command;
import org.bukkit.command.CommandSender;
import org.bukkit.entity.Entity;
import org.bukkit.entity.Player;
import org.bukkit.event.EventHandler;
import org.bukkit.event.Listener;
import org.bukkit.event.entity.PlayerDeathEvent;
import org.bukkit.inventory.ItemStack;
import org.bukkit.plugin.java.JavaPlugin;
import org.bukkit.potion.PotionEffect;

public class TheBase extends JavaPlugin implements Listener {
   
      public void onEnable()
      {
   getServer().getPluginManager().registerEvents(this, this);
}
      @EventHandler
      public void onPlayerDeth(PlayerDeathEvent e) {
        Entity en = e.getEntity();
        if ((en instanceof Player)) {
          Player p = (Player)en;
          e.getDrops().clear();
          this.ffa.remove(p.getName());
          this.ffa.remove(p.getName());
          for (PotionEffect effect : p.getActivePotionEffects())
            p.removePotionEffect(effect.getType());
         
        }
      }
      @SuppressWarnings({ "unchecked", "rawtypes" })
      public ArrayList<String> ffa = new ArrayList();
    public boolean onCommand(CommandSender sender, Command cmd, String commandLabel, String[] args) {
       

        if (!(sender instanceof Player)) {
                sender.sendMessage(ChatColor.RED + "This plugin is for players only!");
                return true;
        }
       
      
        Player p = (Player) sender;
      
      
        if (cmd.getName().equalsIgnoreCase("setffa") && (p.hasPermission("set.ffa"))) {
           
           
                getConfig().set("ffa.world", p.getLocation().getWorld().getName());
                getConfig().set("ffa.x", p.getLocation().getX());
                getConfig().set("ffa.y", p.getLocation().getY());
                getConfig().set("ffa.z", p.getLocation().getZ());
                saveConfig();
                p.sendMessage("§7§o[§c§oFFA§7§o] §e§oThe §a§oFFA §e§owas set successfully.");
               
                return true;
        }
       
        if (cmd.getName().equalsIgnoreCase("ffa")) {
            if (getConfig().getConfigurationSection("ffa") == null) {
                if (this.ffa.contains(p.getName())) {
                    p.sendMessage("§7§o[§c§oFFA§7§o] §c§oThe §a§oFFA §c§ois not set.");
                    return true;
            }
            World w = Bukkit.getServer().getWorld(getConfig().getString("ffa.world"));
            double x = getConfig().getDouble("ffa.x");
            double y = getConfig().getDouble("ffa.y");
            double z = getConfig().getDouble("ffa.z");
            p.teleport(new Location(w, x, y, z));
            p.getInventory().addItem(new ItemStack[] { new ItemStack(Material.IRON_SWORD) });
            p.getInventory().addItem(new ItemStack[] { new ItemStack(Material.BOW) });
            p.getInventory().addItem(new ItemStack[] { new ItemStack(Material.FISHING_ROD) });
            p.getInventory().addItem(new ItemStack[] { new ItemStack(Material.ARROW) });
            p.getInventory().addItem(new ItemStack[] { new ItemStack(Material.ARROW) });
            p.getInventory().addItem(new ItemStack[] { new ItemStack(Material.ARROW) });
            p.getInventory().addItem(new ItemStack[] { new ItemStack(Material.ARROW) });
            p.getInventory().addItem(new ItemStack[] { new ItemStack(Material.ARROW) });
            p.getInventory().addItem(new ItemStack[] { new ItemStack(Material.ARROW) });
            p.getInventory().addItem(new ItemStack[] { new ItemStack(Material.ARROW) });
            p.getInventory().addItem(new ItemStack[] { new ItemStack(Material.ARROW) });
            p.getInventory().addItem(new ItemStack[] { new ItemStack(Material.ARROW) });
            p.getInventory().addItem(new ItemStack[] { new ItemStack(Material.ARROW) });
            p.getInventory().addItem(new ItemStack[] { new ItemStack(Material.ARROW) });
            p.getInventory().addItem(new ItemStack[] { new ItemStack(Material.ARROW) });
           
            p.sendMessage("§7§o[§c§oFFA§7§o] §e§oYou have been teleported to §a§oFFA§e§o arena.");
            this.ffa.add(p.getName());
            return true;
    }
            p.sendMessage("§7§o[§c§oFFA§7§o] §c§oYou aren't allowed to do this.");
            return true;
        }
    }


}

 

Add: player.updateInventory();

And if you get an error please post the error