AppSync Events - Closed channels receiving subscription events

[stocaaro]

Describe the bug
Following the Connect to AWS AppSyncEvents docs example in a vite react app causes duplicate events to arrive for every sent event when running under npm run dev.

This is because the useEffect is run twice in dev mode and the channel.close is running (maybe before the subscription is fully formed).

To Reproduce

1. Pull down this sample app, run sandbox and launch npm run dev.
2. Setup a user
3. Click "Publish Event" to see the events experience with duplicates
4. Click "Publish Todo" to see the data create subscription without duplicates
5. See the browser console for id specific events noting the opening/closing of different subscriptions

Expected behavior
I would expect channel subscriptions for events to not present duplicates in the same way that the data subscriptions doesn't duplicate events.

Screenshots

Desktop (please complete the following information):

• OS: OS X 15.3.1 (24D70)
• Browser Chrome
• Version 133.0.6943.127