Program: 83636
Project: 83636
Buggy source:
/** 
 * Load this player configuration from disk.
 */
public void load(){
  this.configFolder=new File(this.plugin.getDataFolder(),this.playerName);
  this.configFolder.mkdirs();
  this.generalConfig=YamlConfiguration.loadConfiguration(new File(this.configFolder,GENERAL_CONFIG_FILENAME));
  this.warpConfig=YamlConfiguration.loadConfiguration(new File(this.configFolder,WARP_CONFIG_FILENAME));
  this.quotaConfig=YamlConfiguration.loadConfiguration(new File(this.configFolder,QUOTA_CONFIG_FILENAME));
  if (this.plugin.getPrivateWarps().get(this.playerName) == null) {
    this.plugin.getPrivateWarps().put(this.playerName,new HashMap<String,Warp>());
  }
  this.plugin.getConfigurationManager().loadWarps(this.warpConfig,this.plugin.getPrivateWarps().get(this.playerName));
  ConfigurationSection homeSection=this.generalConfig.getConfigurationSection(OWConfigurationManager.HOME_KEY);
  if (homeSection != null) {
    this.plugin.setDefaultHome(this.playerName,new Warp(this.plugin,TEMP_HOME_NAME,homeSection).getLocation());
  }
  ConfigurationSection multiworldHomesSection=this.generalConfig.getConfigurationSection(OWConfigurationManager.MULTIWORLD_HOMES_KEY);
  if (multiworldHomesSection != null) {
    for (    String worldName : multiworldHomesSection.getKeys(false)) {
      this.plugin.setHome(this.playerName,worldName,new Warp(this.plugin,TEMP_HOME_NAME,multiworldHomesSection.getConfigurationSection(worldName)).getLocation());
    }
  }
  ConfigurationSection backSection=this.generalConfig.getConfigurationSection(OWConfigurationManager.BACK_KEY);
  if (backSection != null) {
    this.plugin.getLocationTracker().setPreviousLocation(this.playerName,new Warp(this.plugin,TEMP_BACK_NAME,backSection).getLocation());
  }
  List<?> warpStackSections=this.generalConfig.getList(OWConfigurationManager.STACK_KEY);
  if (warpStackSections != null) {
    Stack<Location> warpStack=new Stack<Location>();
    for (    Object section : warpStackSections) {
      System.out.println("String_Node_Str" + section.getClass());
      warpStack.push(new Warp(this.plugin,TEMP_STACK_NAME,(ConfigurationSection)section).getLocation());
    }
    this.plugin.getLocationTracker().setLocationStack(this.playerName,warpStack);
  }
  this.plugin.getQuotaManager().getPlayerMaxPublicWarps().put(this.playerName,this.quotaConfig.getInt(OWConfigurationManager.QUOTAS_KEY + "String_Node_Str" + OWConfigurationManager.QUOTA_PUBLIC_KEY,OWQuotaManager.QUOTA_UNDEFINED));
  this.plugin.getQuotaManager().getPlayerMaxPrivateWarps().put(this.playerName,this.quotaConfig.getInt(OWConfigurationManager.QUOTAS_KEY + "String_Node_Str" + OWConfigurationManager.QUOTA_PRIVATE_KEY,OWQuotaManager.QUOTA_UNDEFINED));
}

Fixed version (ground truth):
/** 
 * Load this player configuration from disk.
 */
public void load(){
  this.configFolder=new File(this.plugin.getDataFolder(),this.playerName);
  this.configFolder.mkdirs();
  this.generalConfig=YamlConfiguration.loadConfiguration(new File(this.configFolder,GENERAL_CONFIG_FILENAME));
  this.warpConfig=YamlConfiguration.loadConfiguration(new File(this.configFolder,WARP_CONFIG_FILENAME));
  this.quotaConfig=YamlConfiguration.loadConfiguration(new File(this.configFolder,QUOTA_CONFIG_FILENAME));
  if (this.plugin.getPrivateWarps().get(this.playerName) == null) {
    this.plugin.getPrivateWarps().put(this.playerName,new HashMap<String,Warp>());
  }
  this.plugin.getConfigurationManager().loadWarps(this.warpConfig,this.plugin.getPrivateWarps().get(this.playerName));
  ConfigurationSection homeSection=this.generalConfig.getConfigurationSection(OWConfigurationManager.HOME_KEY);
  if (homeSection != null) {
    this.plugin.setDefaultHome(this.playerName,new Warp(this.plugin,TEMP_HOME_NAME,homeSection).getLocation());
  }
  ConfigurationSection multiworldHomesSection=this.generalConfig.getConfigurationSection(OWConfigurationManager.MULTIWORLD_HOMES_KEY);
  if (multiworldHomesSection != null) {
    for (    String worldName : multiworldHomesSection.getKeys(false)) {
      this.plugin.setHome(this.playerName,worldName,new Warp(this.plugin,TEMP_HOME_NAME,multiworldHomesSection.getConfigurationSection(worldName)).getLocation());
    }
  }
  ConfigurationSection backSection=this.generalConfig.getConfigurationSection(OWConfigurationManager.BACK_KEY);
  if (backSection != null) {
    this.plugin.getLocationTracker().setPreviousLocation(this.playerName,new Warp(this.plugin,TEMP_BACK_NAME,backSection).getLocation());
  }
  List<?> warpStackSections=this.generalConfig.getList(OWConfigurationManager.STACK_KEY);
  if (warpStackSections != null) {
    Stack<Location> warpStack=new Stack<Location>();
    for (    Object o : warpStackSections) {
      warpStack.push(new Warp(this.plugin,TEMP_STACK_NAME,(Map)o).getLocation());
    }
    this.plugin.getLocationTracker().setLocationStack(this.playerName,warpStack);
  }
  this.plugin.getQuotaManager().getPlayerMaxPublicWarps().put(this.playerName,this.quotaConfig.getInt(OWConfigurationManager.QUOTAS_KEY + "String_Node_Str" + OWConfigurationManager.QUOTA_PUBLIC_KEY,OWQuotaManager.QUOTA_UNDEFINED));
  this.plugin.getQuotaManager().getPlayerMaxPrivateWarps().put(this.playerName,this.quotaConfig.getInt(OWConfigurationManager.QUOTAS_KEY + "String_Node_Str" + OWConfigurationManager.QUOTA_PRIVATE_KEY,OWQuotaManager.QUOTA_UNDEFINED));
}