Spectate Plugin not working properly.

I've been coding a spectate plugin, it used to work, but now every time someone uses the command /spec on, it says an internal error has occured while attempting to perform this command. Heres my code.

Code:

public static ArrayList<String> players = new ArrayList<>();
    public static ArrayList<String> spectators = new ArrayList<>();
   
    public boolean onCommand(CommandSender sender, Command cmd, String label, String[] args){
        if(cmd.getName().equalsIgnoreCase("spec")){
            if(!sender.hasPermission("donor.spectate")){
                sender.sendMessage("§8[§eSGFFA§8] §cYou must be a donor to do that, http://store.sgffa.us");
                return true;
            }
           
            if(args.length == 0 || args.length < 1){
                sender.sendMessage("§8[§6SGFFA§8] §fYou can either /spec on, or /spec off.");
            }
           
            if(args[0].equalsIgnoreCase("on") || args[0].equalsIgnoreCase("off")){
            if(args[0].equalsIgnoreCase("on") && args.length == 1){
                Player p = (Player) sender;
                spectators.add(p.getName());
                players.remove(p.getName());
                p.setFlying(true);
                p.setAllowFlight(true);
                for(Player pall : Bukkit.getOnlinePlayers()){
                    pall.hidePlayer(p);
                    p.getInventory().clear();
                    p.getInventory().setHelmet(new ItemStack(Material.AIR));
                    p.getInventory().setChestplate(new ItemStack(Material.AIR));
                    p.getInventory().setLeggings(new ItemStack(Material.AIR));
                    p.getInventory().setBoots(new ItemStack(Material.AIR));
                    p.sendMessage("§8[§6SGFFA§8] §fSpectate mode §aenabled§f.");
                    return true;
                    }
                }
           
            if(args[0].equalsIgnoreCase("off") && args.length == 1){
                Player p = (Player) sender;
                spectators.remove(p.getName());
                players.add(p.getName());
                p.setFlying(false);
                p.setAllowFlight(false);
                for(Player pall : Bukkit.getOnlinePlayers()){
                    pall.showPlayer(p);
                    p.kickPlayer("§8[§6SGFFA§8] §fThis will be fixed soon.");
                    return true;
                }
            }
        }
    }
        return true;
}
   
    @EventHandler
    public void onJoin(PlayerJoinEvent e){
        Player p = e.getPlayer();
        players.add(p.getName());
        spectators.remove(p.getName());
        p.setFlying(false);
        p.setAllowFlight(false);
    }
   
    @EventHandler
    public void onHit(EntityDamageByEntityEvent e){
        if(e.getDamager() instanceof Player){
            Player p = (Player) e.getDamager();
            if(e.getEntity() instanceof LivingEntity){
                if(spectators.contains(p.getName())){
                    e.setCancelled(true);
                }
            }
        }
    }
   
    @EventHandler
    public void onLeave(PlayerQuitEvent e){
        Player p = e.getPlayer();
        players.add(p.getName());
        spectators.remove(p.getName());
        p.setFlying(false);
        p.setAllowFlight(false);
    }
   
    @EventHandler
    public void onDeath(PlayerDeathEvent e){
        Player p = e.getEntity();
        spectators.remove(p.getName());
        players.add(p.getName());
    }
}

 

@Luflexed you also need to check if the command sender is a player. This will throw an error if the console or a command block executes /spec.

 

@Techy4198 it does not bother me if console throws an error. It's the plugin that's not working.

 

@Luflexed please post the error log.