empty manifest file

[ThePeach]

Hello all, I am currently with Shakapacker v6.5.2, as I'm going through the update from Webpacker v4.
I just stumbled in a problem that I cannot solve and I was wondering if I am doing anything wrong.
My config file webpacker.yml contains the following:

default: &default
  source_path: app/assets
  source_entry_path: /javascript
  nested_entries: false
  public_root_path: public
  public_output_path: packs
...

But if I try to output the config from my webpack.config.js I get:

{
  mode: 'development',
  output: {
    filename: 'js/[name].js',
    chunkFilename: 'js/[name].chunk.js',
    hotUpdateChunkFilename: 'js/[id].[fullhash].hot-update.js',
    path: '/Users/peach/repos/myapp/public/packs',
    publicPath: '/packs/'
  },
  entry: {},
  resolve: {
    extensions: [
      '.js',         '.jsx',
      '.mjs',        '.ts',
      '.tsx',        '.coffee',
      '.mjs',        '.js',
      '.jsx',        '.scss',
      '.css',        '.module.scss',
      '.module.css', '.png',
      '.svg',        '.gif',
      '.jpeg',       '.jpg',
      '.yml'
    ],
    modules: [ '/Users/peach/repos/myapp/app/assets', 'node_modules' ]
  },
....

and clearly the public/packs/manifest.json is an empty object :(

[ThePeach]

As a memento to future generations: it was a typo. javascripts instead of javascript