fix: Fix handling of contributor_ids sanitization

Signed-off-by: Shadi Sharaf <shady@sharaf.me>

Author: shadyvb

classes/class-wpcom-liveblog-rest-api.php

@@ -660,6 +660,10 @@ public static function sanitize_numeric( $param, $request, $key ) {
 	 */
 	public static function get_json_param( $param, $json ) {
 		if ( isset( $json[ $param ] ) ) {
+			// Handle arrays (e.g., contributor_ids from multi-select)
+			if ( is_array( $json[ $param ] ) ) {
+				return array_map( 'html_entity_decode', $json[ $param ] );
+			}
 			return html_entity_decode( $json[ $param ] );
 		}
 		return false;