404 page not found entries in the error log file

On every page load, I get these two entries in my error log file.

Code:

ERROR - 2016-04-22 15:26:44 --> 404 Page Not Found: Assets/js
ERROR - 2016-04-22 15:26:45 --> 404 Page Not Found: Assets/js

I have absolute no idea what is causing these errors as both assets & js are valid folders. Is there any way I can get more info on which specific call is causing this 404 error or page referer etc info will be useful to resolve it.