JTextArea not painted in its actual state

ADDITIONAL SYSTEM INFORMATION :
win10, java 1.8.211

A DESCRIPTION OF THE PROBLEM :
JTextarea text disappears when you erase the text in a JTextfield, both in the same Jpanel

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
1.) run the code
2.) resize the window (not fullscreen)
3.) hit send
repeate:
    - clear the text
    - write some new text
    - resize the window(not fullscreen)
    - hit send


   





EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
when you earse the text in the JTextfield, the JTextarea should not be changed
ACTUAL -
last text you send to the JTextarea disapears

---------- BEGIN SOURCE ----------
public class BugTester {

    public static void main(String[] args) {
        MainFrame frame = new MainFrame();
    }

    public static class MainFrame extends JFrame implements ActionListener {

        private JTextField textField;
        private JTextArea textArea;

        public MainFrame() throws HeadlessException {
            super();
            this.setSize(800, 800);
            this.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
            this.setLocationRelativeTo(null);
            init();
            this.pack();
            this.setVisible(true);

        }

        private void init() {

            JPanel panel = new JPanel();
            panel.setLayout(new GridLayout(3, 3));

            textField = new JTextField("hello");
            panel.add(textField);
            panel.setSize(new Dimension(300, 300));
            panel.setMinimumSize(new Dimension(300, 300));
            panel.setMaximumSize(new Dimension(300, 300));


            JButton button = new JButton("send");
            button.setSize(100, 50);
            button.addActionListener(this);
            button.setActionCommand("send");
            panel.add(button);

            textArea = new JTextArea();
            textArea.setSize(200, 200);
            panel.add(textArea);

            this.add(panel);
        }
        @Override
        public void actionPerformed(ActionEvent e) {

            String command = e.getActionCommand();
            if (command.equals("send")) {

                String message = textField.getText();
                textArea.append(message+ " ");
            }

        }

    }
}
---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
revalidate;
repaint;

FREQUENCY : often