This is an internal library. If you just want to lint your pug templates, use eslint-plugin-vue-pug.
npm install
npm run setupAdding errors to the templateBody.errors array doesn't actually seem to affect linting at all, but I found this https://github.com/vuejs/eslint-plugin-vue/blame/master/lib/rules/no-parsing-error.js/