SEARCH ERROR: Catchable fatal error:Object of class WP_Error could not be converted

When I Search on my site I get

Catchable fatal error: Object of class WP_Error could not be converted to string in REMOVED ADDRESS /wp-content/themes/atahualpa/functions/bfa_postinfo.php on line 308

Line 308 is blank....

// Author website link
LINE 308
if ( strpos($postinfo_string,'%author-link%') !== FALSE ) {

ob_start();

the_author_link();

$author_link = ob_get_contents();

ob_end_clean();

$postinfo = str_replace("%author-link%", $author_link, $postinfo);

}

I am a newbie and have no idea what I am doing!
Please advise. Thanks So Much and God Bless.
~Angela