First argument should be an array in /home/estanda1/public_html/includes/templates/theme339/common/html_header.php on line 51

My website:e-standard got above issue, the main page works okay for anyone,normal visit will not pop up this error ,only the crawler,but i could not figure out what's going on and how to fix this problem,it seems i did not make change on line 51,i would be appreciate if any expert could help