function assertNoClosureStylePlaceholdersInIcuTemplate(icuTemplate) {
  const match = CLOSURE_PLACEHOLDER_RE.exec(icuTemplate);
  assert(
      match == null,
      'closure-style placeholder: "%s" found in ICU template: "%s"',
      match && match[0], icuTemplate);
}
@param {string} icuTemplate
@throws an AssertionError if the string contains closure-style placeholders
  (`'{$name} is a closure-style placeholder'`)