code: function getDefaultEntries() {
    let result = {}
  
    const PROJECT_MAIN = join(PROJECT_SRC_DIR, 'main.js')
    const PROJECT_INDEX = join(PROJECT_SRC_DIR, 'index.js')
  
    if (existsSync(PROJECT_MAIN))
      result.main = PROJECT_MAIN
  
    if (existsSync(PROJECT_INDEX))
      result.index = PROJECT_INDEX
  
    return result
  }
docs: By default, the shared configuration look for 2 entries, this is useful when
  your project act both as an app by running the “main.js” and a library by
  allowing the “index.js” to be imported.