Node component of theme may not like null url

Using Radix theme with Mercury threw an error due to the node.component.yml specifying type string for the url but receiving null. I made a patch for the radix theme

https://www.drupal.org/project/radix/issues/3504961 🐛 Null node url causes error with Mercury editor Active

Maintainer accepted but wondered if maybe Mercury should pass empty string instead of null (which might fix this problem for any other themes that similarly define the node component url as only a string type).