Comments: Verify 'mirroring' property exists in media views.

Checks that the media collection has a mirroring property before accessing the property in media views.

Props MMDeveloper, mukesh27.
Fixes #53856.

Built from https://develop.svn.wordpress.org/trunk@52671


git-svn-id: http://core.svn.wordpress.org/trunk@52260 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/js/media-views.js

@@ -2116,7 +2116,7 @@ AttachmentsBrowser = View.extend(/** @lends wp.media.view.AttachmentsBrowser.pro
 			mediaFoundHasMoreResultsMessage = __( 'Number of media items displayed: %d. Scroll the page for more results.' );
 		}
 
-		if ( this.collection.mirroring.args.s ) {
+		if ( this.collection.hasOwnProperty('mirroring') && this.collection.mirroring.args.s ) {
 			count = this.collection.length;
 
 			if ( 0 === count ) {

wp-includes/version.php

@@ -16,7 +16,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '6.0-alpha-52670';
+$wp_version = '6.0-alpha-52671';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.