Package vignette with \VignetteEngine{} not specifying an engine package:
  ‘ensurer.Rmd’
Engines should be specified as \VignetteEngine{PKG::ENG}.
Package vignette with \VignetteEngine{} not specifying an engine package:
  ‘ensurer.Rmd’
Engines should be specified as \VignetteEngine{PKG::ENG}.
Package vignette with \VignetteEngine{} not specifying an engine package:
  ‘ensurer.Rmd’
Engines should be specified as \VignetteEngine{PKG::ENG}.
Package vignette with \VignetteEngine{} not specifying an engine package:
  ‘ensurer.Rmd’
Engines should be specified as \VignetteEngine{PKG::ENG}.
Package vignette with \VignetteEngine{} not specifying an engine package:
  'ensurer.Rmd'
Engines should be specified as \VignetteEngine{PKG::ENG}.
Package vignette with \VignetteEngine{} not specifying an engine package:
  ‘ensurer.Rmd’
Engines should be specified as \VignetteEngine{PKG::ENG}.