message: Fix book build on ci
diff: set -euo pipefail
  main() {
  - pushd book
  - pushd highlight.js
  - npm install
  - node tools/build.js pikelet pikelet-repl rust bash
  - popd
  -
  - mkdir -p src/theme
  - cp highlight.js/build/highlight.pack.js src/theme/highlight.js
  - popd
  + mdbook build book
  }
  main
  