v1.20.0

v1.20.0 (minor)

Changes since v1.19.0:

• Assert the issue list is empty, and say what is in it when it is not (@Claude)
• Let a generator that cannot ship here register itself (@Claude)

What's Changed

• Let a generator that cannot ship here register itself by @matt-edmondson in #157

Full Changelog: v1.19.0...v1.20.0