Don't crash on when adding certs with null url's .
Don't crash on when adding certs with null url's .

ekr/nss-old,nmav/nss,ekr/nss-old,ekr/nss-old,nmav/nss,ekr/nss-old,ekr/nss-old,nmav/nss,ekr/nss-old,nmav/nss,nmav/nss,nmav/nss,ekr/nss-old,nmav/nss