Index: src/wp-content/themes/twentynineteen/inc/template-functions.php
===================================================================
--- src/wp-content/themes/twentynineteen/inc/template-functions.php	(revision 51542)
+++ src/wp-content/themes/twentynineteen/inc/template-functions.php	(working copy)
@@ -101,7 +101,7 @@
  * @origin Twenty Nineteen 1.0
  *
  * @param array $attr  Attributes for the image markup.
- * @return string Value for use in post thumbnail 'sizes' attribute.
+ * @return array $attr Values for use in post thumbnail 'sizes' attribute.
  */
 function twentynineteen_post_thumbnail_sizes_attr( $attr ) {