Index: wp-content/themes/twentyfifteen/inc/template-tags.php
===================================================================
--- wp-content/themes/twentyfifteen/inc/template-tags.php	(revision 39994)
+++ wp-content/themes/twentyfifteen/inc/template-tags.php	(working copy)
@@ -97,7 +97,7 @@
 		}
 
 		$tags_list = get_the_tag_list( '', _x( ', ', 'Used between list items, there is a space after the comma.', 'twentyfifteen' ) );
-		if ( $tags_list ) {
+		if ( $tags_list && ! is_wp_error( $tags_list ) ) {
 			printf( '<span class="tags-links"><span class="screen-reader-text">%1$s </span>%2$s</span>',
 				_x( 'Tags', 'Used before tag names.', 'twentyfifteen' ),
 				$tags_list