Catchable fatal error: Object of class WP_Error could not be converted to string

I think the error began occurring after I deleted a few unused tags:

Catchable fatal error: Object of class WP_Error could not be converted to string in /brisbanebite.com.au/wp-content/themes/foodpress/functions.php on line 348

According to Dreamweaver, 348 is this:
cho get_category_parents($cat, TRUE, ' ' . $delimiter . ' ');

Surrounding it is this:

$post_type->labels->singular_name . '</a> ' . $delimiter . ' ';
        echo $before . get_the_title() . $after;
      } else {
        $cat = get_the_category(); $cat = $cat[0];
<strong>        echo get_category_parents($cat, TRUE, ' ' . $delimiter . ' ');</strong>
        echo $before . get_the_title() . $after;
      }

I have no idea how to fix this. Can anyone throw me a bone?