I want to test weather array of custom type objects are empty or not . Here '?' is not checking empty and running the code and failing in case empty messageArray.

messageArray?.forEach((message: BannerMessage) => {
      const outPutMessageObj: OutPutMessage = this.getOutPutMessageObject(message);
      processedMessages.push(outPutMessageObj);
    });

The error i am getting is

Uncaught (in promise) TypeError: messageArray.forEach is not a function