NullpointerException

I have a nullpointer exception which is found at this class at line 108, I cant squash this so help would be useful

Code:

public static void startGame(String arena) {
 
        Bukkit.getServer().broadcastMessage("worked!");
        File path = new File(plugin.getDataFolder() + "/Arena");
        File data = new File(path, "Arenas.yml");
        YamlConfiguration arenas = new YamlConfiguration();
 
        if (!(path.exists())) {
            path.mkdir();
        }
       
        if(!(data.exists())) {
            try {
                data.createNewFile();
            } catch (IOException e) {
                System.out.println("Failed to create file");
            }
        }
       
            try {
                arenas.load(data);
            } catch (FileNotFoundException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            } catch (InvalidConfigurationException e) {
                e.printStackTrace();
            }       
       
       
        Bukkit.getServer().broadcastMessage("Worked!");
 
        int i = 1;
 
        for (Player p : plugin.getServer().getOnlinePlayers()) {
            int x = arenas.getInt("arenas.list." + arena + ".spawns.list." + i + ".location.x");
            int y = arenas.getInt("arenas.list." + arena + ".spawns.list." + i + ".location.y");
            int z = arenas.getInt("arenas.list." + arena + ".spawns.list." + i + ".location.z");
            String s = arenas.getString("arenas.list." + arena + ".location.world");
 
            i++;
 
            World world = Bukkit.getServer().getWorld(s);
 
            Location loc = new Location(world, x, y, z);
 
            p.sendMessage(x + ", " + y + ", " + z + ", " + world.getName());
            plugin.ingame.put(p.getName(), true);
            plugin.lives.put(p.getName(), 3);
 
            p.teleport(loc);
 
        }
    }

Is broadcast's Worked once and not twice meaning it does not get past the first stage

 

What is line 108?

 

File path = new File(plugin.getDataFolder() + "/Arena");

It is on a timer and works when it runs the second time though so i am really confused

 

The only thing that would explain that NPE is that the variable plugin is null i.e hasn't been initialized/assigned at that point. Also make sure that method startArena needs to be static since you might be trying to access instance data.