code: def check_assets(self):
          
          if not self.assets_file:
              raise ImproperlyConfigured("You must specify the path to the assets.json file via WEBPACK_ASSETS_FILE")
          elif not os.path.exists(self.assets_file):
              raise ImproperlyConfigured(
                  "The file `{file}` was not found, make sure to run the webpack build before the collectstatic command".format(
                      file=self.assets_file))
docs: Throws an exception if assets file is not configured or cannot be found.
          :param assets: path to the assets file