open_uri on invalid URLs

Hi

I am using open(public_url) in one of the modules and it works fine as
long as public_url is a valid URL. But when i give an invalid URL, i do
not have control on error raised- My application fails and log shows :

Errno::ENOENT) \\\"No such file or directory

How can i catch these exceptions?

Regards,
Sandeep G