Post without title

[fornaeffe]

Blogger allows posts without title, but if I run node index.js b ... against a backup of a blog with some posts without title, I get an error from sanitize function: "Input must be a string".

I resolved by manually adding a title to the only two posts without a title in .xml file, but I think it would be better manage this case in the script.

However, thank you very much for this script, it saved me lot of time!