v4.2.1

What's Changed

• Troubleshooting improvements for component errors by @ericyhwang in #642
  • In development, warn if a component's init() is improperly an async or Promise-returning function
  • If registering a singleton component that extends Component, eagerly throw an error at component registration time, instead of at render-time throwing an obscure "Uncaught TypeError: Cannot read properties of undefined (reading 'controller')"

Documentation updates

These were already deployed to https://derbyjs.github.io/derby/ upon PR merge.

• [docs] Improvements to Racer model docs by @ericyhwang in #641
• Troubleshooting guides for various errors by @ericyhwang in #642
• Add Typedoc generated API docs by @craigbeck in #638

Full Changelog: v4.2.0...v4.2.1