depcheck has not seen a release in a while and it would be great to get an idea about how the upgrade path would look like.

First, some observations:

• depcheck is widely used and running in legacy and current systems
• The latest release as of today, v1.4.3 was released Jan 2022, over a year ago
• Some well-needed maintenance changes have happened on master since and would benefit 1.x users in a drop-in update
  • There are also some dependencies that could be bumped for non-breaking improvements
  • After a quick look, the only thing that stands out as semver-major is addressed in chore: downgrade sass to unbreak node 10 #798
• depcheck currently indicates Node.js >=10. v10 reached EoL 2021-04-30 and has fallen out of use
• If generous compatibility is still desired, it's worth to note that current stable versions of Debian and Ubuntu both have node v12 in distribution repositories

So with that in mind, this would make sense to me:

1. Release 1.5.0 based on current main (with any breaking changes addressed/reverted/omitted)
2. Increase node.engines to ^12.22.12 || ^14.19 || ^16 || >=18
3. Release 2.0.0

Then:

• users on older environments/codebases can still get drop-in replacements addressing npm audit issues, security advisories, bug fixes, stability updates and likelier to have less duplicated dependency versions
  • consider also unmaintained libraries currently depdending on some depcheck@^1
• v1 can be fully deprecated and users pointed to v2
• when at any point (soon or in the future) the choice is made to make a new breaking v3 release, v2 can be kept as a maintenance/support target only receiving security updates and the occasional dependency bump.