EditorsKitのリンク機能が使えない、動かなかったので別のプラグインを拡張してみた

<?php
/*
Plugin Name: Custom Cover Link
Description: Extends the core Cover block to add a custom link.
Version: 1.0
Author: calcs
*/

function enqueue_custom_block_editor_assets() {
    wp_enqueue_script(
        'custom-cover-link',
        plugin_dir_url(__FILE__) . 'custom-cover-link.js',
        array('wp-blocks', 'wp-element', 'wp-editor', 'wp-components', 'wp-block-editor'),
        filemtime(plugin_dir_path(__FILE__) . 'custom-cover-link.js'),
        true
    );
    wp_enqueue_style(
        'custom-cover-link-style',
        plugin_dir_url(__FILE__) . 'custom-cover-link.css',
        array(),
        filemtime(plugin_dir_path(__FILE__) . 'custom-cover-link.css')
    );
}
add_action('enqueue_block_editor_assets', 'enqueue_custom_block_editor_assets');

function enqueue_custom_block_frontend_assets() {
    wp_enqueue_style(
        'custom-cover-link-style',
        plugin_dir_url(__FILE__) . 'custom-cover-link.css',
        array(),
        filemtime(plugin_dir_path(__FILE__) . 'custom-cover-link.css')
    );
}
add_action('wp_enqueue_scripts', 'enqueue_custom_block_frontend_assets');

function add_block_link($block_content, $block) {
    // カバーブロックの場合
    if ('core/cover' === $block['blockName'] && isset($block['attrs']['link'])) {
        $link = $block['attrs']['link'];
        if (!empty($link)) {
            $block_content = '<a href="' . esc_url($link) . '" class="cover-link">' . $block_content . '</a>';
        }
    }

    // グループブロックの場合
    if ('core/group' === $block['blockName'] && isset($block['attrs']['link'])) {
        $link = $block['attrs']['link'];
        if (!empty($link)) {
            $block_content = '<a href="' . esc_url($link) . '" class="group-link">' . $block_content . '</a>';
        }
    }

    // カラムブロックの場合
    if ('core/column' === $block['blockName'] && isset($block['attrs']['link'])) {
        $link = $block['attrs']['link'];
        if (!empty($link)) {
            $block_content = '<a href="' . esc_url($link) . '" class="column-link">' . $block_content . '</a>';
        }
    }

    return $block_content;
}
add_filter('render_block', 'add_block_link', 10, 2);

(function(wp) {
    const { registerBlockType } = wp.blocks;
    const { createHigherOrderComponent } = wp.compose;
    const { InspectorControls, __experimentalLinkControl } = wp.blockEditor;
    const { PanelBody, ToolbarButton, Popover, Button } = wp.components;
    const { Fragment, useState, createElement } = wp.element;

    // リンク機能を拡張する共通の関数
    const withCustomLink = (BlockEdit, blockType) => {
        return (props) => {
            if (props.name !== blockType) {
                return createElement(BlockEdit, props);
            }

            const { attributes: { link }, setAttributes } = props;
            const [isLinkPickerOpen, setIsLinkPickerOpen] = useState(false);

            const openLinkPicker = () => setIsLinkPickerOpen(true);
            const closeLinkPicker = () => setIsLinkPickerOpen(false);

            const removeLink = () => {
                setAttributes({ link: '' }); // リンクを空に設定
            };

            return createElement(
                Fragment,
                null,
                createElement(BlockEdit, props),
                createElement(
                    InspectorControls,
                    null,
                    createElement(
                        PanelBody,
                        { title: 'リンク設定' },
                        createElement(
                            ToolbarButton,
                            {
                                icon: 'admin-links',
                                label: 'リンクを編集',
                                onClick: openLinkPicker,
                            }
                        ),
                        isLinkPickerOpen && createElement(
                            Popover,
                            { position: "middle center", onClose: closeLinkPicker },
                            createElement(
                                __experimentalLinkControl,
                                {
                                    value: { url: link },
                                    onChange: (value) => setAttributes({ link: value.url }),
                                }
                            )
                        ),
                        link && createElement(
                            Button,
                            {
                                isDestructive: true,
                                onClick: removeLink,
                            },
                            'リンクを削除'
                        )
                    )
                )
            );
        };
    };

    // カバーブロックの拡張
    const withCustomCoverLink = createHigherOrderComponent(
        (BlockEdit) => withCustomLink(BlockEdit, 'core/cover'), 
        'withCustomCoverLink'
    );

    // グループブロックの拡張
    const withCustomGroupLink = createHigherOrderComponent(
        (BlockEdit) => withCustomLink(BlockEdit, 'core/group'), 
        'withCustomGroupLink'
    );

    // カラムブロックの拡張
    const withCustomColumnLink = createHigherOrderComponent(
        (BlockEdit) => withCustomLink(BlockEdit, 'core/column'), 
        'withCustomColumnLink'
    );

    // フィルターフックに追加
    wp.hooks.addFilter(
        'editor.BlockEdit',
        'custom/with-custom-cover-link',
        withCustomCoverLink
    );

    wp.hooks.addFilter(
        'editor.BlockEdit',
        'custom/with-custom-group-link',
        withCustomGroupLink
    );

    wp.hooks.addFilter(
        'editor.BlockEdit',
        'custom/with-custom-column-link',
        withCustomColumnLink
    );

    // ブロック保存の修正
    const withCustomSave = (element, blockType, attributes) => {
        if (blockType.name !== 'core/cover' && blockType.name !== 'core/group' && blockType.name !== 'core/column') {
            return element;
        }

        const { link } = attributes;

        if (!link) {
            return element;
        }

        const className = blockType.name === 'core/cover' ? 'cover-link' : blockType.name === 'core/group' ? 'group-link' : 'column-link';

        return createElement(
            'a',
            { href: link, className: className },
            element
        );
    };

    wp.hooks.addFilter(
        'blocks.getSaveElement',
        'custom/with-custom-save',
        withCustomSave
    );
})(window.wp);