Switching Themes… getting line error

Im moving a site to a different them and before I clicked “Activate” on the new theme I clicked “Preview” and got this …

Warning: Invalid argument supplied for foreach() in /home3/donkon26/public_html/midweststreetryders.com/wp-content/themes/rhapsody/header.php on line 51

I didn’t activate the new theme yet because I wanted to see what others thought first. Is there a fix that anyone can see based off that message?

Thanks