Shopping page error

I came across an error on my site’s shop, it presents under each listing, and I’m not sure how to fix..

Warning: join(): Invalid arguments passed in /public_html/…/wp-includes/category-template.php on line 1260

When I inspect file, line 1260 is:
return $before . join( $sep, $term_links ) . $after;

Any help would be appreciated.

• This topic was modified 6 years ago by username201701. Reason: added line item argument