message: do not fail if folder does not exist yet (the composer vendor folder does not exist yet)
diff: add_to_PATH () {
  for d; do
  - d=$({ cd -- "$d" && { pwd -P || pwd; } } 2>/dev/null) # canonicalize symbolic links
  - if [ -z "$d" ]; then continue; fi # skip nonexistent directory
  case ":$PATH:" in
  *":$d:"*) :;;
  *) PATH=$d:$PATH;;
  