fix: improve error handling in message handlers

[AhyoungRyu]

Fixes some of comments in SBISSUE-17017

Problem

Users currently need to return an empty object from onBeforeSendFileMessage due to type constraints. Additionally, error handling for message sending failures needs improvement to ensure eventHandlers.message callbacks (onSendMessageFailed, onUpdateMessageFailed, onFileUploadFailed) are properly triggered when errors occur within their corresponding onBefore handlers (onBeforeSendUserMessage, onBeforeSendFileMessage, etc).

Solution

• Allow void return type in onBeforeXXX handler
• Add proper error handling via eventHandlers.message for:
  • onSendMessageFailed
  • onUpdateMessageFailed
  • onFileUploadFailed

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[HoonBaek]

LGTM!

[bang9]

@HoonBaek @AhyoungRyu The onBeforeHandler is essentially something the user injects, so I don't think we need to handle errors for them—they should be able to handle that themselves.

What the customer seems to want is to handle failures when sending messages using SDK.
Shouldn't it be handled like this?

try {
  const params = await onBeforeSendUserMessage(...);
  return await sendUserMessage(params); // -> here
} catch (error) {
  // Error: Receiver is blocked
  eventHandlers.message.onSendMessageFailed(error);
}

[bang9]

I also reviewed the ticket that led to this requirement, and it seems they don’t actually need error handling but rather additional processing after a file message has been successfully sent.

In the onBeforeHandler, they are sending the file message separately, performing additional processing for it, and then throwing an error to cancel the actual message send operation.

This error ends up being an uncaught error, which is why they are requesting a handler.

This implementation is quite strange, so wouldn’t it be better to provide a handler for post-send operations instead?

const params = await onBeforeSendUserMessage(...);
const message = await sendUserMessage(params);
await onAfterSendUserMessage(message, params);
return message;

onAfterSendFileMessage={async (message, params) => {
  if (isValidImage(params)) {
      uploadImageToS3({
        params,
        channelId: currentChannelId.current,
        messageId: message.messageId.toString(),
      }).then(() => {
        handleImageSentAnalytics(sbChannel, userId, env.name);    
      });
  }
}}