Error on frontend

I’m seeing this error on my site’s homepage: “Notice: unserialize(): Error at offset 0 of 76 bytes in /home/biome/public_html/wp-content/plugins/rss-feed-widget/functions.php on line 229”

This is the line of code it’s referring to:
$rss_links = (is_array(unserialize($instance[‘rss_url’]))?unserialize($instance[‘rss_url’]):array());

Any ideas how to remove this? The plugin otherwise seems to be working fine.