ADDITIONAL SYSTEM INFORMATION :
macOS Catalina10.15.1
Java 1.8u201

A DESCRIPTION OF THE PROBLEM :
If you enable VoiceOver in Accessibility settings, run the test program and select the File->Crash menu, the application will crash.

The test program has a TextField with some text. The menu item simply replaces that text with a shorter string.

The exception thrown is:
Exception in thread "JavaFX Application Thread" java.lang.StringIndexOutOfBoundsException: String index out of range: 9
at java.lang.String.substring(String.java:1963)
at com.sun.glass.ui.mac.MacAccessible.accessibilityAttributeValueForParameter(MacAccessible.java:1823)

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Enable VoiceOver in Accessibility Settings
Run the supplied test program
Select the File->Crash menu
Crash

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
Application shouldn't crash
ACTUAL -
Exception in thread "JavaFX Application Thread" java.lang.StringIndexOutOfBoundsException: String index out of range: 9
at java.lang.String.substring(String.java:1963)
at com.sun.glass.ui.mac.MacAccessible.accessibilityAttributeValueForParameter(MacAccessible.java:1823)

---------- BEGIN SOURCE ----------
import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.control.Menu;
import javafx.scene.control.MenuBar;
import javafx.scene.control.MenuItem;
import javafx.scene.control.TextField;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;

public class HelloWorld extends Application
{

    @Override
    public void start(
        Stage primaryStage)
    {
        TextField textField1 = new TextField();
        textField1.setText("some text");
        
        MenuBar menuBar = new MenuBar();
        menuBar.setUseSystemMenuBar(true);
        Menu menuFile = new Menu("File");
        menuBar.getMenus().addAll(menuFile);
        
        MenuItem add = new MenuItem("Crash");
        add.setOnAction(e -> textField1.setText("text"));
        menuFile.getItems().add(add);
        
        VBox root = new VBox();
        root.getChildren().add(textField1);

        Scene scene = new Scene(root, 300, 250);

        ((VBox) scene.getRoot()).getChildren().addAll(menuBar);
        primaryStage.setTitle("Hello World!");
        primaryStage.setScene(scene);
        primaryStage.show();
        

    }

    public static void main(
        String[] args)
    {
        launch(args);
    }
}
---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
Don't use VoiceOver

FREQUENCY : always