相关疑难解决方法(0)

我正在尝试重建使用Firebase Cloud Functions和Firestore的Web应用程序示例。部署功能时，出现以下错误：

src/index.ts:45:18 - error TS2532: Object is possibly 'undefined'.
45     const data = change.after.data();

这是功能：

export const archiveChat = functions.firestore
  .document("chats/{chatId}")
  .onUpdate(change => {
    const data = change.after.data();

    const maxLen = 100;
    const msgLen = data.messages.length;
    const charLen = JSON.stringify(data).length;

    const batch = db.batch();

    if (charLen >= 10000 || msgLen >= maxLen) {

      // Always delete at least 1 message
      const deleteCount = msgLen - maxLen <= 0 ? 1 : msgLen - maxLen
      data.messages.splice(0, deleteCount);

      const ref …