Program: 173847
Project: 173847
Buggy source:
public void actionPerformed(ActionEvent actor){
  String command=actor.getActionCommand();
  List<PossibleAction> actions=((ActionTaker)actor.getSource()).getPossibleActions();
  PossibleAction executedAction=null;
  if (actions != null && actions.size() > 0) {
    executedAction=actions.get(0);
  }
  if (command.equals(BUY_CMD)) {
    process(executedAction);
  }
 else   if (command.equals(SELL_CMD)) {
    process(executedAction);
  }
 else   if (command.equals(DONE_CMD) || command.equals(PASS_CMD)) {
    if (GameManager.isGameOver()) {
      System.exit(0);
    }
    process(executedAction);
  }
 else   if (command.equals(SWAP_CMD)) {
    SpecialSRProperty sp=(SpecialSRProperty)stockRound.getSpecialProperties().get(0);
    if (sp instanceof ExchangeForShare) {
      ((ExchangeForShare)sp).execute();
      extraButton.setText("String_Node_Str");
      extraButton.setEnabled(false);
      extraButton.setVisible(false);
    }
  }
 else   if (command.equals(QUIT_CMD))   System.exit(0);
 else   if (command.equals(SAVE_CMD))   new JFileChooser().showSaveDialog(this);
 else   if (command.equals(REPORT_CMD)) {
    GameUILoader.reportWindow.setVisible(((JMenuItem)actor.getSource()).isSelected());
    return;
  }
 else   if (command.equals(MARKET_CMD)) {
    GameUILoader.stockChart.setVisible(((JMenuItem)actor.getSource()).isSelected());
  }
 else   if (command.equals(MAP_CMD)) {
    GameUILoader.orWindow.setVisible(((JMenuItem)actor.getSource()).isSelected());
  }
 else   if (command.equals(UNDO_CMD)) {
    process(executedAction);
  }
 else   if (command.equals(FORCED_UNDO_CMD)) {
    process(executedAction);
  }
 else   if (command.equals(REDO_CMD)) {
    process(executedAction);
  }
}

Fixed version (ground truth):
public void actionPerformed(ActionEvent actor){
  String command=actor.getActionCommand();
  List<PossibleAction> actions=null;
  if (actor.getSource() instanceof ActionTaker) {
    actions=((ActionTaker)actor.getSource()).getPossibleActions();
  }
  PossibleAction executedAction=null;
  if (actions != null && actions.size() > 0) {
    executedAction=actions.get(0);
  }
  if (command.equals(BUY_CMD)) {
    process(executedAction);
  }
 else   if (command.equals(SELL_CMD)) {
    process(executedAction);
  }
 else   if (command.equals(DONE_CMD) || command.equals(PASS_CMD)) {
    if (GameManager.isGameOver()) {
      System.exit(0);
    }
    process(executedAction);
  }
 else   if (command.equals(SWAP_CMD)) {
    SpecialSRProperty sp=(SpecialSRProperty)stockRound.getSpecialProperties().get(0);
    if (sp instanceof ExchangeForShare) {
      ((ExchangeForShare)sp).execute();
      extraButton.setText("String_Node_Str");
      extraButton.setEnabled(false);
      extraButton.setVisible(false);
    }
  }
 else   if (command.equals(QUIT_CMD))   System.exit(0);
 else   if (command.equals(SAVE_CMD))   new JFileChooser().showSaveDialog(this);
 else   if (command.equals(REPORT_CMD)) {
    GameUILoader.reportWindow.setVisible(((JMenuItem)actor.getSource()).isSelected());
    return;
  }
 else   if (command.equals(MARKET_CMD)) {
    GameUILoader.stockChart.setVisible(((JMenuItem)actor.getSource()).isSelected());
  }
 else   if (command.equals(MAP_CMD)) {
    GameUILoader.orWindow.setVisible(((JMenuItem)actor.getSource()).isSelected());
  }
 else   if (command.equals(UNDO_CMD)) {
    process(executedAction);
  }
 else   if (command.equals(FORCED_UNDO_CMD)) {
    process(executedAction);
  }
 else   if (command.equals(REDO_CMD)) {
    process(executedAction);
  }
}