Matthew Haines-Young mattheu

If you have a dynamic gutenberg block, and in the PHP render_callback, your code includes a custom query and loop, then it will break the editor.

This test plugin demonstrates the issue.

Create a new page.
Add the 'Demo Dynamic Post Block' block
Add one or more image IDs. Comma separated (e.g. 12, 523 )
Save a draft.
If you preview the page - this will work as expected. You will see the image titles and IDs.
If you reload the page in the editor, the page will break with the following JS error:

	<?php
	/**
	* Plugin Name: Speculative Loading Eager Prerender
	* Description: Overrides WordPress speculative loading rules to use "eager" and "prerender" for better perceived performance.
	* Version: 1.0
	* Author: Your Name
	*/

	add_filter(
	'wp_speculation_rules_configuration',

	<?php
	/**
	* Plugin Name: Speculative Loading Eager Prerender Demo Plugin
	* Description: Overrides WordPress speculative loading rules to use "eager" and "prerender" for better perceived performance.
	* Version: 1.0
	* Author: Matthew Haines-Young
	*/

	// Hook into the filter WordPress uses to generate the speculationrules script.
	add_filter('wp_speculation_rules', function($rules) {

	<?php
	/**
	* Defer loading of scripts until consent given (using Altis consent API).
	*
	* Note this requires the script to be enqueued in the normal manner.
	* Scripts are loaded async so must be compatible with this, can't have dependencies etc.
	*
	* @package
	*/

	import withUniqueId from './with-unique-id';

	function FormField({
	id,
	label,
	value,
	onChange,
	}) {
	return (
	<div>

	// Make sure you specify the script "wp-annotations" as a dependency of your code that uses the WP annotations API.

	const { select, dispatch } = wp.data;

	const ANNOTATION_NS = 'core/annotations';
	const ANNOTATION_SOURCE = 'testing-annotations';

	// Default attributes for blockTypes.
	// richTextIdentifier - this is the ID of the richTextField we want to add the annotation to.
	const blockTypes = {

	/* global wp */

	import edit from './edit';
	import defaultOptions from '../default';
	const { __ } = wp.i18n;

	export const name = 'rbmh/ad';

	export default Edit;

	const { subscribe } = wp.data;
	const { createBlock } = wp.blocks;

	const createAdBlock = () => createBlock( AdBlock.name, { size: 'mpu' } );

	subscribe( e => {
	const {
	getBlocks,
	} = wp.data.select( 'core/editor' );

	// Array of blocks to hide.
	// This could come from anywhere - we use localize script and change the blocks to hide depending on post type.
	const hiddenBlocks = [ 'hm/myBlock' ];

	// Use function below to filter block settings.
	// Will hide all 'hiddenBlocks' from the inserter UI
	// But if those blocks are already present, or somehow get into the content, they will still work.
	wp.hooks.addFilter(
	'blocks.registerBlockType',
	'hm-gb-blocks/modify-core-blocks',

	/* global wp */

	import React from 'react';
	import ReactDOM from 'react-dom';
	import PropTypes from 'proptypes';

	const { Component } = wp.element;

	class Iframe extends Component {
	propTypes = {