Editor: Check for null values in Theme JSON to cater for blockGap.

When resolving theme.json preset variables, add a check to make sure the value is not empty before we run it through strpos() and preg_match_all().

Props ramonopoly, mukesh27, get_dave.
Fixes #60613.
Built from https://develop.svn.wordpress.org/trunk@57716


git-svn-id: http://core.svn.wordpress.org/trunk@57217 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/class-wp-theme-json.php

@@ -3857,12 +3857,18 @@ class WP_Theme_JSON {
 	 * Replaces CSS variables with their values in place.
 	 *
 	 * @since 6.3.0
+	 * @since 6.5.0 Check for empty style before processing its value.
+	 *
 	 * @param array $styles CSS declarations to convert.
 	 * @param array $values key => value pairs to use for replacement.
 	 * @return array
 	 */
 	private static function convert_variables_to_value( $styles, $values ) {
 		foreach ( $styles as $key => $style ) {
+			if ( empty( $style ) ) {
+				continue;
+			}
+
 			if ( is_array( $style ) ) {
 				$styles[ $key ] = self::convert_variables_to_value( $style, $values );
 				continue;

wp-includes/version.php

@@ -16,7 +16,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '6.5-beta2-57715';
+$wp_version = '6.5-beta2-57716';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.