The new core_version_requirement key is breaking drupal sites that up to date with 8.7.7
As reported by Ravi Lamontagne:
The 'core_version_requirement' can not be used to specify compatibility for a specific version before 8.7.7
This is caused by #2 (closed), so we should remove that key again until we have a use case to indicate a version-relying above 8.7.7
So the error exists because we used that key for a version older than 8.7.7. It is quite the edge case I think