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