code: def display_index(config):
      
      browser = config["web browser"].lower()
      data_dir = Path(config["data dir"])
      if browser in webbrowser._browsers:
          b = webbrowser.get(browser)
      else:
          if browser != "default":
              logger.warning(
                  "Couldn't find '%s' browser. Falling back to default.", browser
              )
          b = webbrowser.get()
      index_file = data_dir.joinpath("index.html")
      if not index_file.exists():
          logger.error("File doesn't exist: %s", index_file.as_posix())
          raise FileNotFoundError("Index file doesn't exist")
      else:
          logger.info("Opening %s in '%s'", index_file.as_posix(), b.name)
          b.open(index_file.as_uri())
docs: Open index in web browser.
  
      Parameters
      ----------
      config : Config
          Configuration settings.
  
      Raises
      ------
      FileNotFoundError
          If index file doesn't exist.