This was original reported here:
https://github.com/AdoptOpenJDK/openjdk-support/issues/4

I was able to reproduce this with latest jdk/jdk on Fedora 30. It appears the original fix in 8, JDK-7123957, regressed via JDK-8145547.

Steps:

    Install the gnome-tweak-tool

    sudo add-apt-repository universe
    sudo apt install gnome-tweak-tool

    Run the following code snippet

    import javax.swing.*;

    public class ThemeCrash {
        public static void main(String ... args) {
            SwingUtilities.invokeLater(() -> {
                try {
                    UIManager.setLookAndFeel(UIManager.setLookAndFeel("com.sun.java.swing.plaf.gtk.GTKLookAndFeel"););
                    JOptionPane.showMessageDialog(null, "test");
                } catch (Throwable ignore) { }
            });
        }
    }

    Observe that the "Ok" button can be clicked.

    Launch Gnome Tweak Tool. From the "Appearance" tab, change the theme from "Adwaita (default)" to "Adwaita-dark"

    Observe that the "Ok" button can no longer be clicked.