Program: 34064
Project: 34064
Buggy source:
/** 
 * Dynamically creates an inventory of challenges for the player showing the level
 * @param player
 * @param level
 * @return inventory
 */
public Inventory challengePanel(Player player,String level){
  List<CPItem> cp=new ArrayList<CPItem>();
  if (level.isEmpty() && !challengeList.containsKey("String_Node_Str")) {
    if (!Settings.challengeLevels.isEmpty()) {
      level=Settings.challengeLevels.get(0);
    }
 else {
      plugin.getLogger().severe("String_Node_Str");
      Inventory error=Bukkit.createInventory(null,9,plugin.myLocale(player.getUniqueId()).challengesguiTitle);
      player.sendMessage(ChatColor.RED + plugin.myLocale(player.getUniqueId()).errorCommandNotReady);
      return error;
    }
  }
  for (  String challengeName : challengeList.get(level)) {
    CPItem item=createItem(challengeName,player);
    if (item != null) {
      cp.add(item);
    }
  }
  int levelDone=0;
  for (int i=0; i < Settings.challengeLevels.size(); i++) {
    if (i == 0) {
      levelDone=0;
    }
 else {
      levelDone=checkLevelCompletion(player,Settings.challengeLevels.get(i - 1));
    }
    if (!level.equalsIgnoreCase(Settings.challengeLevels.get(i))) {
      List<String> lore=new ArrayList<String>();
      if (levelDone <= 0) {
        CPItem item=new CPItem(Material.BOOK_AND_QUILL,ChatColor.GOLD + Settings.challengeLevels.get(i),null,null);
        lore=Util.chop(ChatColor.WHITE,plugin.myLocale(player.getUniqueId()).challengesNavigation.replace("String_Node_Str",Settings.challengeLevels.get(i)),25);
        item.setNextSection(Settings.challengeLevels.get(i));
        item.setLore(lore);
        cp.add(item);
      }
 else {
        CPItem item=new CPItem(Material.BOOK,ChatColor.GOLD + Settings.challengeLevels.get(i),null,null);
        lore=Util.chop(ChatColor.WHITE,plugin.myLocale(player.getUniqueId()).challengestoComplete.replace("String_Node_Str",String.valueOf(levelDone)).replace("String_Node_Str",Settings.challengeLevels.get(i - 1)),25);
        item.setLore(lore);
        cp.add(item);
      }
    }
  }
  if (!level.equals("String_Node_Str")) {
    for (    String freeChallenges : challengeList.get("String_Node_Str")) {
      CPItem item=createItem(freeChallenges,player);
      if (item != null) {
        cp.add(item);
      }
    }
  }
  if (cp.size() > 0) {
    int size=cp.size() + 8;
    size-=(size % 9);
    Inventory newPanel=Bukkit.createInventory(null,size,plugin.myLocale(player.getUniqueId()).challengesguiTitle);
    playerChallengeGUI.put(player.getUniqueId(),cp);
    for (    CPItem i : cp) {
      newPanel.addItem(i.getItem());
    }
    return newPanel;
  }
  return null;
}

Fixed version (ground truth):
/** 
 * Dynamically creates an inventory of challenges for the player showing the level
 * @param player
 * @param level
 * @return inventory
 */
public Inventory challengePanel(Player player,String level){
  List<CPItem> cp=new ArrayList<CPItem>();
  if (level.isEmpty() && !challengeList.containsKey("String_Node_Str")) {
    if (!Settings.challengeLevels.isEmpty()) {
      level=Settings.challengeLevels.get(0);
    }
 else {
      plugin.getLogger().severe("String_Node_Str");
      Inventory error=Bukkit.createInventory(null,9,plugin.myLocale(player.getUniqueId()).challengesguiTitle);
      player.sendMessage(ChatColor.RED + plugin.myLocale(player.getUniqueId()).errorCommandNotReady);
      return error;
    }
  }
  for (  String challengeName : challengeList.get(level)) {
    CPItem item=createItem(challengeName,player);
    if (item != null) {
      cp.add(item);
    }
  }
  int levelDone=0;
  for (; levelDone < Settings.challengeLevels.size(); levelDone++) {
    if (checkLevelCompletion(player,Settings.challengeLevels.get(levelDone)) > 0) {
      break;
    }
  }
  for (int i=0; i < Settings.challengeLevels.size(); i++) {
    if (!level.equalsIgnoreCase(Settings.challengeLevels.get(i))) {
      List<String> lore=new ArrayList<String>();
      if (i <= levelDone) {
        CPItem item=new CPItem(Material.BOOK_AND_QUILL,ChatColor.GOLD + Settings.challengeLevels.get(i),null,null);
        lore=Util.chop(ChatColor.WHITE,plugin.myLocale(player.getUniqueId()).challengesNavigation.replace("String_Node_Str",Settings.challengeLevels.get(i)),25);
        item.setNextSection(Settings.challengeLevels.get(i));
        item.setLore(lore);
        cp.add(item);
      }
 else {
        CPItem item=new CPItem(Material.BOOK,ChatColor.GOLD + Settings.challengeLevels.get(i),null,null);
        int toDo=checkLevelCompletion(player,Settings.challengeLevels.get(i - 1));
        lore=Util.chop(ChatColor.WHITE,plugin.myLocale(player.getUniqueId()).challengestoComplete.replace("String_Node_Str",String.valueOf(toDo)).replace("String_Node_Str",Settings.challengeLevels.get(i - 1)),25);
        item.setLore(lore);
        cp.add(item);
      }
    }
  }
  if (!level.equals("String_Node_Str") && challengeList.containsKey("String_Node_Str")) {
    for (    String freeChallenges : challengeList.get("String_Node_Str")) {
      CPItem item=createItem(freeChallenges,player);
      if (item != null) {
        cp.add(item);
      }
    }
  }
  if (cp.size() > 0) {
    int size=cp.size() + 8;
    size-=(size % 9);
    Inventory newPanel=Bukkit.createInventory(null,size,plugin.myLocale(player.getUniqueId()).challengesguiTitle);
    playerChallengeGUI.put(player.getUniqueId(),cp);
    for (    CPItem i : cp) {
      newPanel.addItem(i.getItem());
    }
    return newPanel;
  }
  return null;
}