Program: 133977
Project: 133977
Buggy source:
public static void login(BendingPlayer pl){
  ProjectKorra plugin=ProjectKorra.plugin;
  Player player=Bukkit.getPlayer(pl.getUUID());
  if (player == null) {
    return;
  }
  if (GeneralMethods.toggledOut.contains(player.getUniqueId())) {
    GeneralMethods.getBendingPlayer(player.getName()).toggleBending();
    player.sendMessage(ChatColor.YELLOW + "String_Node_Str");
  }
  Preset.loadPresets(player);
  String append="String_Node_Str";
  ChatColor color=null;
  boolean chatEnabled=ProjectKorra.plugin.getConfig().getBoolean("String_Node_Str");
  if ((player.hasPermission("String_Node_Str") || GeneralMethods.getBendingPlayer(player.getName()).getElements().size() > 1) && chatEnabled) {
    append=plugin.getConfig().getString("String_Node_Str");
    color=ChatColor.valueOf(plugin.getConfig().getString("String_Node_Str"));
  }
 else   if (GeneralMethods.isBender(player.getName(),Element.Air) && chatEnabled) {
    append=plugin.getConfig().getString("String_Node_Str");
    color=AirMethods.getAirColor();
  }
 else   if (GeneralMethods.isBender(player.getName(),Element.Water) && chatEnabled) {
    append=plugin.getConfig().getString("String_Node_Str");
    color=WaterMethods.getWaterColor();
  }
 else   if (GeneralMethods.isBender(player.getName(),Element.Earth) && chatEnabled) {
    append=plugin.getConfig().getString("String_Node_Str");
    color=EarthMethods.getEarthColor();
  }
 else   if (GeneralMethods.isBender(player.getName(),Element.Fire) && chatEnabled) {
    append=plugin.getConfig().getString("String_Node_Str");
    color=FireMethods.getFireColor();
  }
 else   if (GeneralMethods.isBender(player.getName(),Element.Chi) && chatEnabled) {
    append=plugin.getConfig().getString("String_Node_Str");
    color=ChiMethods.getChiColor();
  }
  if (chatEnabled) {
    player.setDisplayName(player.getName());
    player.setDisplayName(color + append + ChatColor.RESET+ player.getDisplayName());
  }
  if (player.getGameMode() != GameMode.CREATIVE) {
    HashMap<Integer,String> bound=GeneralMethods.getBendingPlayer(player.getName()).getAbilities();
    for (    String str : bound.values()) {
      if (str.equalsIgnoreCase("String_Node_Str") || str.equalsIgnoreCase("String_Node_Str") || str.equalsIgnoreCase("String_Node_Str")) {
        final Player fplayer=player;
        new BukkitRunnable(){
          public void run(){
            fplayer.setFlying(false);
            fplayer.setAllowFlight(false);
          }
        }
.runTaskLater(ProjectKorra.plugin,2);
        break;
      }
    }
  }
}

Fixed version (ground truth):
public static void login(BendingPlayer pl){
  ProjectKorra plugin=ProjectKorra.plugin;
  Player player=Bukkit.getPlayer(pl.getUUID());
  if (player == null) {
    return;
  }
  if (GeneralMethods.toggledOut.contains(player.getUniqueId())) {
    GeneralMethods.getBendingPlayer(player.getName()).toggleBending();
    player.sendMessage(ChatColor.YELLOW + "String_Node_Str");
  }
  Preset.loadPresets(player);
  String append="String_Node_Str";
  ChatColor color=null;
  boolean chatEnabled=ProjectKorra.plugin.getConfig().getBoolean("String_Node_Str");
  if (GeneralMethods.getBendingPlayer(player.getName()).getElements().size() > 1 && chatEnabled) {
    append=plugin.getConfig().getString("String_Node_Str");
    color=ChatColor.valueOf(plugin.getConfig().getString("String_Node_Str"));
  }
 else   if (GeneralMethods.isBender(player.getName(),Element.Air) && chatEnabled) {
    append=plugin.getConfig().getString("String_Node_Str");
    color=AirMethods.getAirColor();
  }
 else   if (GeneralMethods.isBender(player.getName(),Element.Water) && chatEnabled) {
    append=plugin.getConfig().getString("String_Node_Str");
    color=WaterMethods.getWaterColor();
  }
 else   if (GeneralMethods.isBender(player.getName(),Element.Earth) && chatEnabled) {
    append=plugin.getConfig().getString("String_Node_Str");
    color=EarthMethods.getEarthColor();
  }
 else   if (GeneralMethods.isBender(player.getName(),Element.Fire) && chatEnabled) {
    append=plugin.getConfig().getString("String_Node_Str");
    color=FireMethods.getFireColor();
  }
 else   if (GeneralMethods.isBender(player.getName(),Element.Chi) && chatEnabled) {
    append=plugin.getConfig().getString("String_Node_Str");
    color=ChiMethods.getChiColor();
  }
 else {
    append="String_Node_Str";
    color=ChatColor.WHITE;
  }
  if (chatEnabled) {
    player.setDisplayName(player.getName());
    player.setDisplayName(color + append + ChatColor.RESET+ player.getDisplayName());
  }
  if (player.getGameMode() != GameMode.CREATIVE) {
    HashMap<Integer,String> bound=GeneralMethods.getBendingPlayer(player.getName()).getAbilities();
    for (    String str : bound.values()) {
      if (str.equalsIgnoreCase("String_Node_Str") || str.equalsIgnoreCase("String_Node_Str") || str.equalsIgnoreCase("String_Node_Str")) {
        final Player fplayer=player;
        new BukkitRunnable(){
          public void run(){
            fplayer.setFlying(false);
            fplayer.setAllowFlight(false);
          }
        }
.runTaskLater(ProjectKorra.plugin,2);
        break;
      }
    }
  }
}