Add basic validation to enclosure function (#1028)

Author: pfefferle

CHANGELOG.md

@@ -17,6 +17,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Improved
 
+* Basic enclosure validation
 * More User -> Actor renaming
 * Outsource Constants to a separate file
 * Better handling of `readme.txt` and `README.md`

includes/functions.php

@@ -1006,6 +1006,11 @@ function get_enclosures( $post_id ) {
 
 	$enclosures = array_map(
 		function ( $enclosure ) {
+			// Check if the enclosure is a string.
+			if ( ! $enclosure || ! is_string( $enclosure ) ) {
+				return false;
+			}
+
 			$attributes = explode( "\n", $enclosure );
 
 			if ( ! isset( $attributes[0] ) || ! \wp_http_validate_url( $attributes[0] ) ) {

readme.txt

@@ -138,6 +138,7 @@ For reasons of data protection, it is not possible to see the followers of other
 * Added: Fediverse Preview on post-overview page
 * Added: GitHub action to enforce Changelog updates
 * Added: New contributors
+* Improved: Basic enclosure validation
 * Improved: More User -> Actor renaming
 * Improved: Outsource Constants to a separate file
 * Improved: Better handling of `readme.txt` and `README.md`