HarmonyOS 语法问题

fetchLessonResource() {
  if (this.lessonId) {
    LessonHelper.fetch(this.lessonId)
  }
}

\ud83d\udc46编译正常，加了return后编译异常\ud83d\udc47，这不合理吧：

fetchLessonResource() {
  return
  if (this.lessonId) {
    LessonHelper.fetch(this.lessonId)
  }
}