Themes: Prevent PHP notice thrown in wp_title_parts.

The value passed to the `wp_title_parts` filter is run through `explode()`, but can be empty. This throws a PHP notice.

If value of `$title` is empty, return an empty array without exploding.

Props nexbridge, dhruvang21, tussendoor, michaelreetz, o-o, beee, sabernhardt, sirlouen, nimeshatxecurify, westonruter, sirlouen.
Fixes #61352.
Built from https://develop.svn.wordpress.org/trunk@61108


git-svn-id: http://core.svn.wordpress.org/trunk@60444 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/general-template.php

@@ -1436,7 +1436,7 @@ function wp_title( $sep = '»', $display = true, $seplocation = '' ) {
 	 *
 	 * @param string[] $title_array Array of parts of the page title.
 	 */
-	$title_array = apply_filters( 'wp_title_parts', explode( $t_sep, $title ) );
+	$title_array = apply_filters( 'wp_title_parts', ! empty( $title ) ? explode( $t_sep, $title ) : array() );
 
 	// Determines position of the separator and direction of the breadcrumb.
 	if ( 'right' === $seplocation ) { // Separator on right, so reverse the order.

wp-includes/version.php

@@ -16,7 +16,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '6.9-beta2-61107';
+$wp_version = '6.9-beta2-61108';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.