• fastify/lib/reply.js

  Line 65 in 1ad553d

  throw new Error('You cannot use `send` inside the `onError` hook')

• fastify/lib/wrapThenable.js

  Line 19 in 1ad553d

  reply.res.log.error({ err: new Error(`Promise may not be fulfilled with 'undefined' when statusCode is not 204`) }, `Promise may not be fulfilled with 'undefined' when statusCode is not 204`)

I propose we fix those before 2.0.0 is out.