NPE with darklaf when using a custom `TreeCellRenderer`

TreeExample.java

package com.weblogism.darklaf;

import com.github.weisj.darklaf.LafManager;
import com.github.weisj.darklaf.theme.DarculaTheme;

import javax.swing.*;
import javax.swing.tree.DefaultMutableTreeNode;
import javax.swing.tree.TreeCellRenderer;
import java.awt.*;

public class TreeExample extends JFrame {

    static class LovelyTreeCellRenderer implements TreeCellRenderer {
        
        @Override
        public Component getTreeCellRendererComponent(JTree tree, Object value, boolean selected, boolean expanded, boolean leaf, int row, boolean hasFocus) {
            final JPanel panel = new JPanel();
            panel.setBorder(BorderFactory.createLineBorder(Color.BLUE));
            final JLabel label = new JLabel(String.valueOf(value));
            panel.add(label);
            return panel;
        }
    }

    public TreeExample() {
        setTitle("Lorem Ipsum");
        // Deliberately keep window narrow to ensure labels will not be fully visible.
        setSize(new Dimension(100, 140));
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        DefaultMutableTreeNode root = new DefaultMutableTreeNode("Daft Punk");
        DefaultMutableTreeNode homeworkNode = new DefaultMutableTreeNode("Homework");
        DefaultMutableTreeNode discoveryNode = new DefaultMutableTreeNode("Discovery");
        DefaultMutableTreeNode humanAfterAllNode = new DefaultMutableTreeNode("Human After All");
        DefaultMutableTreeNode randomAccessMemoriesNode = new DefaultMutableTreeNode("Random Access Memories");

        root.add(homeworkNode);
        root.add(discoveryNode);
        root.add(humanAfterAllNode);
        root.add(randomAccessMemoriesNode);

        JPanel mainPanel = new JPanel();
        final JTree tree = new JTree(root);
        tree.setCellRenderer(new LovelyTreeCellRenderer());

        mainPanel.add(new JScrollPane(tree));

        getContentPane().add(mainPanel, BorderLayout.CENTER);
        setVisible(true);
      
        // Once window is visible, hover over the entries in the tree, NPE occurs.
    }


    public static void main(String[] args) {
        SwingUtilities.invokeLater(() -> {
            LafManager.install(new DarculaTheme());
            final TreeExample frame = new TreeExample();
            frame.setVisible(true);
        });
    }
}