Fix error handling for attachments and provide example of delays and streaming in parallel (#54)

# Description
<!-- 
    A brief description of what the PR does/changes.
    Use active voice and present tense, e.g., This PR fixes ...
-->
This PR provides better example of error handling while streaming
attachments. Adds handling of delays and provides an example of
streaming attachments in parallel.

## Connected Issues
<!--
DevRev issue(s) full link(s) (e.g.
https://app.devrev.ai/devrev/works/ISS-123).
-->
https://app.devrev.ai/devrev/works/ISS-217174

## Checklist
- [x] Tests added/updated and ran with `npm run test` OR no tests
needed.
- [x] Code formatted and checked with `npm run lint`.
- [x] Added "How to test" section to the description OR this section is
not needed.

Author: radovanjorgic

code/package-lock.json

@@ -56,7 +56,7 @@
     "yargs": "^17.6.2"
   },
   "dependencies": {
-    "@devrev/ts-adaas": "1.9.0",
+    "@devrev/ts-adaas": "1.11.0",
     "@devrev/typescript-sdk": "1.1.63",
     "axios": "^1.9.0",
     "dotenv": "^16.0.3",

code/package.json

@@ -5,11 +5,11 @@ import {
   ExternalSystemAttachmentStreamingResponse,
   ExtractorEventType,
   processTask,
-  serializeAxiosError,
 } from '@devrev/ts-adaas';
 
 // TODO: Replace with function for fetching attachment streams from the
-// external system. This function should return a stream of the attachment data.
+// external system. This function should return either a stream of the
+// attachment data, a delay or an error.
 async function getFileStream({
   item,
 }: ExternalSystemAttachmentStreamingParams): Promise<ExternalSystemAttachmentStreamingResponse> {
@@ -20,22 +20,28 @@ async function getFileStream({
       responseType: 'stream',
       headers: {
         'Accept-Encoding': 'identity',
+        timeout: 30000,
       },
     });
 
     return { httpStream: fileStreamResponse };
   } catch (error) {
     if (axios.isAxiosError(error)) {
-      console.warn(`Error while fetching attachment ${id} from URL.`, serializeAxiosError(error));
-      console.warn('Failed attachment metadata', item);
-    } else {
-      console.warn(`Error while fetching attachment ${id} from URL.`, error);
-      console.warn('Failed attachment metadata', item);
+      if (error?.response?.status === 429) {
+        const retryAfter = error.response?.headers['retry-after'];
+        return { delay: retryAfter };
+      } else {
+        return {
+          error: {
+            message: `Error while fetching attachment ${id} from URL. Error code: ${error.response?.status}. Error message: ${error.response?.data.message}.`,
+          },
+        };
+      }
     }
 
     return {
       error: {
-        message: `Failed to fetch attachment ${id} from URL.`,
+        message: `Unknown error while fetching attachment ${id} from URL. Error: ${error}.`,
       },
     };
   }
@@ -46,6 +52,10 @@ processTask({
     try {
       const response = await adapter.streamAttachments({
         stream: getFileStream,
+
+        // TODO: If needed you can specify how many attachments to stream at
+        // once. Minimum is 1 and maximum is 50.
+        // batchSize: 10,
       });
 
       if (response?.delay) {