Bug: AppSync events onSubscribe resolver return type should be ignored

[dreamorosi]

Expected Behavior

When I create an onSubscribe handler using the AppSyncEventsResolver from the Event Handler utility I should not have to worry about mistakenly breaking subscriptions, if I leave a return statement in the handler.

Current Behavior

Whenever the onSubscribe handler returns something the subscription will fail with this error:

{
  "errorType": "HandlerExecutionError",
  "message": "Unable to process request"
}

Code snippet

import { Logger, LogLevel } from '@aws-lambda-powertools/logger';
import { AppSyncEventsResolver } from '@aws-lambda-powertools/event-handler/appsync-events';
import type { Context } from 'aws-lambda';

const logger = new Logger({
  serviceName: 'AppSyncEvents',
  logLevel: LogLevel.DEBUG,
});
const app = new AppSyncEventsResolver({ logger });

app.onSubscribe('/foo/*', (event) => {
  logger.debug('New subscription', { channel: event.info.channel.path });

  return true; // this should be ignored
});

export const handler = async (event: unknown, context: Context) =>
  app.resolve(event, context);

Steps to Reproduce

Deploy the code above, and try to subscribe to the foo/* channel.

Possible Solution

Similar to what Powertools for AWS Lambda (Python) does here, we should ignore the return of the onSubscribe handler.

Powertools for AWS Lambda (TypeScript) version

latest

AWS Lambda function runtime

22.x

Packaging format used

npm

Execution logs

[github-actions]

⚠️ COMMENT VISIBILITY WARNING ⚠️

This issue is now closed. Please be mindful that future comments are hard for our team to see.

If you need more assistance, please either tag a team member or open a new issue that references this one.

If you wish to keep having a conversation with other community members under this issue feel free to do so.

[github-actions]

This is now released under v2.19.1 version!