docs: def locate_package_entry_file(working_dir, package_name):
      """
      Locate a single npm package to return its browser or main entry.
      """
  
      basedir = join(working_dir, 'node_modules', package_name)
      package_json = join(basedir, 'package.json')
      if not exists(package_json):
          logger.debug(
              "could not locate package.json for the npm package '%s' in the "
              "current working directory '%s'; the package may have been "
              "not installed, the build process may fail",
              package_name, working_dir,
          )
          return
  
      with open(package_json) as fd:
          package_info = json.load(fd)
  
      if ('browser' in package_info or 'main' in package_info):
          # assume the target file exists because configuration files
          # never lie /s
          return join(
              basedir,
              *(package_info.get('browser') or package_info['main']).split('/')
          )
  
      index_js = join(basedir, 'index.js')
      if exists(index_js):
          return index_js
  
      logger.debug(
          "package.json for the npm package '%s' does not contain a main "
          "entry point", package_name,
      )