Rackup 1.0.1 is broken. The record in [the changelog mentions the removal of requires](https://github.com/rack/rackup/blob/main/releases.md#v101), but the reality is that it removed the modules, [leaving only Rackup::VERSION behind](https://github.com/rack/rackup/tree/v1.0.1/lib/rackup), and broke the compatibility between 1.0.0 and 1.0.1. See https://github.com/lsegal/yard/pull/1607
Rackup 1.0.1 is broken. The record in the changelog mentions the removal of requires, but the reality is that it removed the modules, leaving only Rackup::VERSION behind, and broke the compatibility between 1.0.0 and 1.0.1.
See lsegal/yard#1607