Program: 51683
Project: 51683
Buggy source:
@Override public void onEnable(){
  PluginDescriptionFile pdfFile=this.getDescription();
  if (getServer().getPluginManager().getPlugin("String_Node_Str") != null) {
    RegisteredServiceProvider<Economy> rspEcon=getServer().getServicesManager().getRegistration(Economy.class);
    if (rspEcon != null) {
      economy=rspEcon.getProvider();
      this.logger.info("String_Node_Str" + pdfFile.getName() + "String_Node_Str");
    }
 else {
      this.logger.info("String_Node_Str");
      this.setEnabled(false);
      this.getPluginLoader().disablePlugin(this);
      return;
    }
    RegisteredServiceProvider<Permission> rspPerm=plugin.getServer().getServicesManager().getRegistration(Permission.class);
    if (rspPerm != null) {
      permission=rspPerm.getProvider();
      this.logger.info("String_Node_Str" + pdfFile.getName() + "String_Node_Str");
    }
 else {
      this.logger.info("String_Node_Str" + pdfFile.getName() + "String_Node_Str");
    }
    this.logger.info("String_Node_Str" + pdfFile.getName() + "String_Node_Str"+ pdfFile.getVersion()+ "String_Node_Str");
    cf=new CharacterFactory(TraderNpc.class);
    cf.withName("String_Node_Str");
    if (CitizensAPI.getCharacterManager() != null)     CitizensAPI.getCharacterManager().registerCharacter(cf);
    if (CitizensAPI.getTraitManager() != null)     CitizensAPI.getTraitManager().registerTrait(new TraitFactory(InventoryTrait.class).withName("String_Node_Str").withPlugin(this));
    getServer().getPluginManager().registerEvents((Listener)CitizensAPI.getCharacterManager().getCharacter("String_Node_Str"),this);
    getCommand("String_Node_Str").setExecutor(new TraderCommandExecutor());
    ((TraderNpc)CitizensAPI.getCharacterManager().getCharacter("String_Node_Str")).setEcon(economy);
    plugin=this;
  }
 else {
    this.logger.info("String_Node_Str");
    this.setEnabled(false);
    this.getPluginLoader().disablePlugin(this);
    return;
  }
}

Fixed version (ground truth):
@Override public void onEnable(){
  PluginDescriptionFile pdfFile=this.getDescription();
  if (getServer().getPluginManager().getPlugin("String_Node_Str") != null) {
    RegisteredServiceProvider<Economy> rspEcon=getServer().getServicesManager().getRegistration(Economy.class);
    if (rspEcon != null) {
      economy=rspEcon.getProvider();
      this.logger.info("String_Node_Str" + pdfFile.getName() + "String_Node_Str");
    }
 else {
      this.logger.info("String_Node_Str");
      this.setEnabled(false);
      this.getPluginLoader().disablePlugin(this);
      return;
    }
    RegisteredServiceProvider<Permission> rspPerm=getServer().getServicesManager().getRegistration(Permission.class);
    if (rspPerm != null) {
      permission=rspPerm.getProvider();
      this.logger.info("String_Node_Str" + pdfFile.getName() + "String_Node_Str");
    }
 else {
      this.logger.info("String_Node_Str" + pdfFile.getName() + "String_Node_Str");
    }
    this.logger.info("String_Node_Str" + pdfFile.getName() + "String_Node_Str"+ pdfFile.getVersion()+ "String_Node_Str");
    cf=new CharacterFactory(TraderNpc.class);
    cf.withName("String_Node_Str");
    if (CitizensAPI.getCharacterManager() != null)     CitizensAPI.getCharacterManager().registerCharacter(cf);
    if (CitizensAPI.getTraitManager() != null)     CitizensAPI.getTraitManager().registerTrait(new TraitFactory(InventoryTrait.class).withName("String_Node_Str").withPlugin(this));
    getServer().getPluginManager().registerEvents((Listener)CitizensAPI.getCharacterManager().getCharacter("String_Node_Str"),this);
    getCommand("String_Node_Str").setExecutor(new TraderCommandExecutor());
    ((TraderNpc)CitizensAPI.getCharacterManager().getCharacter("String_Node_Str")).setEcon(economy);
    plugin=this;
  }
 else {
    this.logger.info("String_Node_Str");
    this.setEnabled(false);
    this.getPluginLoader().disablePlugin(this);
    return;
  }
}