Refactor fix for changing styles on the editor

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

@@ -35,7 +35,7 @@ class WP_Theme_JSON {
 	 * @since 5.8.0
 	 * @var array
 	 */
-	protected static $blocks_metadata = null;
+	protected static $blocks_metadata = array();
 
 	/**
 	 * The CSS selector for the top-level styles.
@@ -721,11 +721,12 @@ protected static function append_to_selector( $selector, $to_append, $position =
 	 * @return array Block metadata.
 	 */
 	protected static function get_blocks_metadata() {
-		$registry                = WP_Block_Type_Registry::get_instance();
-		$blocks                  = $registry->get_all_registered();
-		static::$blocks_metadata = array();
-		$blocks                  = array_diff_key( $blocks, static::$blocks_metadata );
-		if ( count( $blocks ) === 0 ) {
+		$registry = WP_Block_Type_Registry::get_instance();
+		$blocks   = $registry->get_all_registered();
+
+		// Is there metadata for all currently registered blocks?
+		$blocks = array_diff_key( $blocks, static::$blocks_metadata );
+		if ( empty( $blocks ) ) {
 			return static::$blocks_metadata;
 		}
 		foreach ( $blocks as $block_name => $block_type ) {