Workaround for amp-onerror validation issues: https://github.com/google/web-stories-wp/issues/7763

web-stories-amp-onerror-workaround.php

<?php
/**
 * Web Stories amp-onerror Workaround plugin bootstrap.
 *
 * @package   Google\Web_Stories_AMP_OnError_Workaround
 * @author    Pascal Birchler, Google
 * @license   GPL-2.0-or-later
 * @copyright 2021 Google Inc.
 *
 * @wordpress-plugin
 * Plugin Name: Web Stories amp-onerror Workaround
 * Plugin URI: https://gist.github.com/swissspidy/3d8503785ca452b82ad21e7c30bc1ac2
 * Description: Prevents AMP validation issues due to recent changes related to amp-onerror.
 * Version: 0.1
 * Author: Pascal Birchler, Google
 * Author URI: https://pascalbirchler.com
 * License: Apache License 2.0
 * License URI: https://www.apache.org/licenses/LICENSE-2.0
 * Gist Plugin URI: https://gist.github.com/swissspidy/3d8503785ca452b82ad21e7c30bc1ac2
 * Update URI: https://gist.github.com/swissspidy/3d8503785ca452b82ad21e7c30bc1ac2
 */

namespace Google\Web_Stories_AMP_OnError_Workaround;

add_filter(
    'amp_optimizer_config',
    static function ( $config ) {
	     $config['transformers'] = array_diff( $config['transformers'], [ \AmpProject\Optimizer\Transformer\AmpBoilerplateErrorHandler::class ] );
	    return $config;
    }
);

add_filter(
    'web_stories_amp_optimizer_config',
    static function ( $config ) {
        if ( is_singular( 'web-story' ) ) {
            $config['transformers'] = array_diff( $config['transformers'], [ \Google\Web_Stories_Dependencies\AmpProject\Optimizer\Transformer\AmpBoilerplateErrorHandler::class ] );
        }
	    return $config;
    }
);