Editor: In `edit-form-blocks.php`, check the result of `wp_set_post_lock()`, which may return `false` and cause a warning when passed to `implode()`.

Props kakshak, aduth.
Fixes #47013.
Built from https://develop.svn.wordpress.org/trunk@45413


git-svn-id: http://core.svn.wordpress.org/trunk@45224 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-admin/edit-form-blocks.php

@@ -247,9 +247,13 @@ if ( $user_id ) {
 } else {
 	// Lock the post.
 	$active_post_lock = wp_set_post_lock( $post->ID );
+	if ( $active_post_lock ) {
+		$active_post_lock = esc_attr( implode( ':', $active_post_lock ) );
+	}
+
 	$lock_details = array(
 		'isLocked'       => false,
-		'activePostLock' => esc_attr( implode( ':', $active_post_lock ) ),
+		'activePostLock' => $active_post_lock,
 	);
 }
 

wp-includes/version.php

@@ -13,7 +13,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '5.3-alpha-45412';
+$wp_version = '5.3-alpha-45413';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.