Yoast SEO problem with the News: Notice: Undefined index: wpseo_sitemaps

I was currently using All-in-one-SEO in my blog, but looking for a solution to send also sitemap to Google News I cam across with Yoast SEO plugin, which is great, but I found this bug when trying to configure 

News SEO for WordPress & Google – Yoast

The problem was:

Notice: Undefined index: wpseo_sitemaps

It breaks your blog installation

This is caused when you have unticked the option to generate the XML sitemap. I had to uninstall the files, so the plugins were no longer recognized and had to reconfigure it.