diff -r c7c34916027a -r 177826044cd9 wp/wp-includes/js/wp-embed.js
--- a/wp/wp-includes/js/wp-embed.js	Mon Oct 14 18:06:33 2019 +0200
+++ b/wp/wp-includes/js/wp-embed.js	Mon Oct 14 18:28:13 2019 +0200
@@ -2,6 +2,7 @@
  * WordPress inline HTML embed
  *
  * @since 4.4.0
+ * @output wp-includes/js/wp-embed.js
  *
  * This file cannot have ampersands in it. This is to ensure
  * it can be embedded in older versions of WordPress.
@@ -28,6 +29,11 @@
 
 	window.wp.receiveEmbedMessage = function( e ) {
 		var data = e.data;
+
+		if ( ! data ) {
+			return;
+		}
+
 		if ( ! ( data.secret || data.message || data.value ) ) {
 			return;
 		}