Theme_JSON_Resolver: check for WP_Post in query.

Props oandregal, mcsf, westonruter, mukesh27.
Fixes #64434.


git-svn-id: https://develop.svn.wordpress.org/trunk@61400 602fd350-edb4-49c9-b593-d223f7449a82

Author: oandregal

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

@@ -515,7 +515,7 @@ public static function get_user_data_from_wp_global_styles( $theme, $create_post
 
 		$global_style_query = new WP_Query();
 		$recent_posts       = $global_style_query->query( $args );
-		if ( count( $recent_posts ) === 1 ) {
+		if ( count( $recent_posts ) === 1 && $recent_posts[0] instanceof WP_Post ) {
 			$user_cpt = get_object_vars( $recent_posts[0] );
 		} elseif ( $create_post ) {
 			$cpt_post_id = wp_insert_post(
@@ -532,7 +532,10 @@ public static function get_user_data_from_wp_global_styles( $theme, $create_post
 				true
 			);
 			if ( ! is_wp_error( $cpt_post_id ) ) {
-				$user_cpt = get_object_vars( get_post( $cpt_post_id ) );
+				$post = get_post( $cpt_post_id );
+				if ( $post instanceof WP_Post ) {
+					$user_cpt = get_object_vars( $post );
+				}
 			}
 		}