You'll have to code defensively assuming that the feed might not have a URL or that URL might fail to parse / have a title.

I might have a different take on the implementation, adding a before_validation :populate_title or something like that which will fill self.config['title']. My hunch is that a before_validation on the SimpleRSS will run before save_config on the DynamicContent.

Longer time it may be worth changing how save_config works, using it in a before_validation might not have been the best place for me to put it (before_save might be more in-line with the expected sequence).  Having your code independent from the save_config method is probably safest.