Hi Hector,
Thanks for following up. We took the issue to DeliciousBrains and they owned it. I believe they have released a patch in their most recent version WP Offload Media 2.5.6. https://deliciousbrains.com/wp-offload-media/whats-new/.
Update:
So, it looks like the error occurs only when WP Offload Media (the pro version) is active. It’s weird that the error logs don’t show anything related to WPOM. I’ll write to them as well.
But Yoast SEO generates XML Sitemaps. I do not want XML Sitemaps but I want the sitemaps to be maintained in simple regular pages.