Program: 78371
Project: 78371
Buggy source:
@Override public void actionPerformed(ActionEvent ae){
  if (ae.getActionCommand().equals("String_Node_Str") && !(textUser.equals("String_Node_Str")) && !(textPwd.equals("String_Node_Str"))) {
    if (proxy.customerAccessDataVerifier(textUser.getText(),new String(textPwd.getPassword()))) {
      GUICustomer guiCustomer=null;
      try {
        guiCustomer=new GUICustomer(textUser.getText());
      }
 catch (      ParseException e) {
        System.out.println("String_Node_Str");
      }
      guiCustomer.setVisible(true);
      setVisible(false);
    }
 else {
      JOptionPane.showMessageDialog(new JFrame(),"String_Node_Str","String_Node_Str",JOptionPane.ERROR_MESSAGE);
      textUser.setText("String_Node_Str");
      textPwd.setText("String_Node_Str");
    }
  }
  if (ae.getActionCommand().equals("String_Node_Str") && !(textUser.equals("String_Node_Str")) && !(textPwd.equals("String_Node_Str"))) {
    if (dogSitterProxy.dogSitterAccessDataVerifier(textUser.getText(),new String(textPwd.getPassword()))) {
      GUIDogSitter guiDogSitter=null;
      try {
        guiDogSitter=new GUIDogSitter(textUser.getText());
      }
 catch (      ParseException e) {
        System.out.println("String_Node_Str");
      }
      guiDogSitter.setVisible(true);
      setVisible(false);
    }
 else {
      JOptionPane.showMessageDialog(new JFrame(),"String_Node_Str","String_Node_Str",JOptionPane.ERROR_MESSAGE);
      textUser.setText("String_Node_Str");
      textPwd.setText("String_Node_Str");
    }
  }
  if (ae.getActionCommand().equals("String_Node_Str")) {
    GUISignUp guiSignUp=new GUISignUp();
    guiSignUp.setVisible(true);
    setVisible(false);
  }
}

Fixed version (ground truth):
@Override public void actionPerformed(ActionEvent ae){
  if (ae.getActionCommand().equals("String_Node_Str") && !(textUser.equals("String_Node_Str")) && !(textPwd.equals("String_Node_Str"))) {
    if (proxy.customerAccessDataVerifier(textUser.getText(),new String(textPwd.getPassword()))) {
      GUICustomer guiCustomer=null;
      try {
        guiCustomer=new GUICustomer(textUser.getText());
      }
 catch (      ParseException e) {
        System.out.println("String_Node_Str");
      }
      guiCustomer.setVisible(true);
      setVisible(false);
    }
 else {
      JOptionPane.showMessageDialog(new JFrame(),"String_Node_Str","String_Node_Str",JOptionPane.ERROR_MESSAGE);
      textUser.setText("String_Node_Str");
      textPwd.setText("String_Node_Str");
    }
  }
  if (ae.getActionCommand().equals("String_Node_Str") && !(textUser.equals("String_Node_Str")) && !(textPwd.equals("String_Node_Str"))) {
    if (dogSitterProxy.dogSitterAccessDataVerifier(textUser.getText(),new String(textPwd.getPassword()))) {
      GUIDogSitter guiDogSitter=null;
      try {
        guiDogSitter=new GUIDogSitter(textUser.getText());
      }
 catch (      ParseException e) {
        System.out.println("String_Node_Str");
      }
      guiDogSitter.setVisible(true);
      setVisible(false);
    }
 else {
      JOptionPane.showMessageDialog(new JFrame(),"String_Node_Str","String_Node_Str",JOptionPane.ERROR_MESSAGE);
      textUser.setText("String_Node_Str");
      textPwd.setText("String_Node_Str");
    }
  }
  if (ae.getActionCommand().equals("String_Node_Str")) {
    GUISignUp guiSignUp=new GUISignUp(guiLogin);
    guiSignUp.setVisible(true);
  }
}