v1.2.1

Bug fix

• Fixed es2015 compatibility

Upcoming breaking changes

When the v1.2.0 was released, a breaking change was unintentionally introduced and you had to target esnext within your TypeScript project to avoid incorrect optimization from your builder (angular/angular-cli#22486).
This is now fixed, so you can now target es2015 again.

This breaking change might be re-introduce with the upcoming v2.0.0 major release.
You can already take a look at the migration guide.