Почему возникает исключение IndexOutOfBoundsException в AbstractListModel

Исключение выходит если запускаю в потоке, а без потока не появляется вроде бы. Как подправить чтоб без бага было.

Exception in thread "AWT-EventQueue-0" java.lang.IndexOutOfBoundsException: Index: 1, Size: 0
at java.util.LinkedList.checkElementIndex(Unknown Source)
at java.util.LinkedList.get(Unknown Source)
at ta.MyListModel.getElementAt(MyListModel.java:31)
at ta.MyListModel.getElementAt(MyListModel.java:1)
at javax.swing.plaf.basic.BasicListUI.updateLayoutState(Unknown Source)
at javax.swing.plaf.basic.BasicListUI.maybeUpdateLayoutState(Unknown Source)
at javax.swing.plaf.basic.BasicListUI.getPreferredSize(Unknown Source)
at javax.swing.JComponent.getPreferredSize(Unknown Source)
at javax.swing.ScrollPaneLayout.layoutContainer(Unknown Source)
at java.awt.Container.layout(Unknown Source)
at java.awt.Container.doLayout(Unknown Source)
at java.awt.Container.validateTree(Unknown Source)
at java.awt.Container.validate(Unknown Source)
at javax.swing.RepaintManager$3.run(Unknown Source)
at javax.swing.RepaintManager$3.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(Unknown Source)
at javax.swing.RepaintManager.validateInvalidComponents(Unknown Source)
at javax.swing.RepaintManager$ProcessingRunnable.run(Unknown Source)
at java.awt.event.InvocationEvent.dispatch(Unknown Source)
at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
at java.awt.EventQueue.access$500(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)

Класс модели

package ta;
import java.math.BigDecimal;
import java.util.LinkedList;
import javax.swing.AbstractListModel;
public class MyListModel extends AbstractListModel<String>{
private static final long serialVersionUID = 1L;
private LinkedList<BigDecimal> listBets;
public LinkedList<BigDecimal> getListBets() {
    return listBets;
}
public void setListBets(LinkedList<BigDecimal> listBets) {
    this.listBets = listBets;
}
public MyListModel(LinkedList<BigDecimal> list) {
    setList(list);
}
public void add(BigDecimal value){
    getList().add(value);
    refresh();      
}
public String getElementAt(int index) {
    return String.format("%.8f", getList().get(index));
}
public int getSize() {
    return getList().size();
}
public LinkedList<BigDecimal> getList(){
    return listBets;
}
public void setList(LinkedList<BigDecimal> list){
    this.listBets = list;
    refresh();
}
public void clear() {
    getList().clear();
    refresh();
}
public void removeSide() {
        getList().removeLast();
        getList().removeFirst();
        refresh();
}
void removeLast(){
    getList().removeLast();
    refresh();
}
public void refresh() {
        fireContentsChanged(this, 0, getSize());
}
}

Класс с методом main

package ta;
import java.awt.EventQueue;
import javax.swing.JFrame;
import javax.swing.JPanel;
import java.awt.BorderLayout;
import java.awt.GridLayout;
import java.util.LinkedList;
import java.util.NoSuchElementException;
import java.util.Random;
import java.util.Scanner;
import javax.swing.JTextArea;
import javax.swing.JScrollPane;
import javax.swing.JList;
import javax.swing.JOptionPane;
import javax.swing.JButton;
import java.awt.event.ActionListener;
import java.math.BigDecimal;
import java.text.ParseException;
import java.awt.event.ActionEvent;
public class TA {
private JFrame frame;
private MyListModel listModelBets;
private JList<String> list;
private JTextArea textArea;
private final String defaultBets = "0.00000001\n0.00000001\n0.00000001\n0.00000001\n0.00000001";
private final boolean win = true;
private final boolean lose = false;
/**
 * Launch the application.
 */
public static void main(String[] args) {
    EventQueue.invokeLater(new Runnable() {
        public void run() {
            try {
                TA window = new TA();
                window.frame.setVisible(true);
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    });
}
/**
 * Create the application.
 */
public TA() {
    listModelBets = new MyListModel(new LinkedList<>());
    initialize();
}
/**
 * Initialize the contents of the frame.
 */
private void initialize() {
    frame = new JFrame();
    frame.setBounds(100, 100, 450, 300);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.getContentPane().setLayout(new BorderLayout(0, 0));
    JPanel panel_2 = new JPanel();
    frame.getContentPane().add(panel_2);
    panel_2.setLayout(new GridLayout(0, 2, 0, 0));
    JPanel panel_1 = new JPanel();
    panel_2.add(panel_1);
    panel_1.setLayout(new BorderLayout(0, 0));
    JScrollPane scrollPane = new JScrollPane();
    panel_1.add(scrollPane);
    textArea = new JTextArea(defaultBets);
    scrollPane.setViewportView(textArea);
    JPanel panel = new JPanel();
    panel_2.add(panel);
    panel.setLayout(new BorderLayout(0, 0));
    JScrollPane scrollPane_1 = new JScrollPane();
    panel.add(scrollPane_1);
    list = new JList<String>(listModelBets);
    scrollPane_1.setViewportView(list);
    JPanel panel_3 = new JPanel();
    frame.getContentPane().add(panel_3, BorderLayout.SOUTH);
    JButton btnNewButton_1 = new JButton("Clear");
    btnNewButton_1.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent arg0) {
            listModelBets.clear();
        }
    });
    panel_3.add(btnNewButton_1);
    JButton btnPlay = new JButton("Play");
    btnPlay.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent arg0) {
            Thread th = new Thread(new Runnable() {
                @Override
                public void run() {
                    for (int i = 0; i < 1000; i++) {
                        boolean result = play();
                        if (result) {
                            if (listModelBets.getSize() == 1) {
                                listModelBets.removeLast();
                            } else if (listModelBets.getSize() > 1) {
                                listModelBets.removeSide();
                            }
                        } else {
                            listModelBets.add(getBet());
                        }
                    }
                }
            });
            th.start();
        }
    });
    panel_3.add(btnPlay);
}
void addBets() {
    Scanner sc = new Scanner(textArea.getText());
    sc.useDelimiter("\\n");
    while (sc.hasNext()) {
        String s = sc.next();
        if (s != null && !s.equals("")) {
            try {
                BigDecimal b = new BigDecimal(s);
                listModelBets.add(b);
            } catch (NumberFormatException ex) {
                // JOptionPane.showMessageDialog(frame, "Enter number
                // value.\nSample 0.00000001");
            }
        }
    }
    sc.close();
}
boolean play() {
    Random rnd = new Random();
    return rnd.nextBoolean();
}
BigDecimal getBet() {
    BigDecimal sum = null;
    if (listModelBets.getSize() > 0) {
        sum = calcSum();
    } else {
        addBets();
        sum = calcSum();
    }
    return sum;
}
BigDecimal calcSum() {
    BigDecimal sum = null;
    try {
        BigDecimal first = listModelBets.getList().getFirst();
        BigDecimal last = listModelBets.getList().getLast();
        sum = first.add(last);
    } catch (NoSuchElementException ex) {
        // stopGame();
        JOptionPane.showMessageDialog(frame, "Enter number value\nin editor bets.\nSample 0.00000001");
    }
    return sum;
}
}