* Add revalidate header and error when invalid
object from getStaticProps

* Make sprCache no-op in dev mode

* Update packages/next/next-server/server/next-server.ts

* Update tests for fixes

* Update getStaticProps error and add test

* Update manifest test

* Add validating revalidate value

* Apply suggestions from code review
Co-Authored-By: NJoe Haddad <joe.haddad@zeit.co>

* Change from error to warning high revalidate value