[isaacroldan]

WHY are these changes introduced?

shopify app dev exits when a client of the /extensions WebSocket sends a text message that is not valid JSON. getOnMessageHandler in packages/app/src/cli/services/dev/extension/websocket/handlers.ts calls JSON.parse on every message without a try/catch. The SyntaxError escapes the socket's message listener as an uncaught exception, and the process stops.

WHAT is this pull request doing?

• Catches the SyntaxError from JSON.parse, logs it with outputDebug, and ignores the message. Other errors still propagate.
• Adds a regression test in handlers.test.ts for a message that is not JSON.
• Adds a patch changeset for @shopify/app.

Before, a client that sends not json stops the dev session:

SyntaxError: Unexpected token 'o', "not json" is not valid JSON

After, the session continues. With --verbose, the CLI prints:

Ignoring websocket message that is not valid JSON: Unexpected token 'o', "not json" is not valid JSON

How to manually test your changes?

1. Run shopify app dev --verbose in an app with a UI extension.
2. Connect a WebSocket client to the dev server at /extensions, for example npx wscat -c ws://localhost:<port>/extensions.
3. Send the text not json.
4. Confirm that app dev keeps running and prints the debug line above.
5. Send a valid message, for example {"event":"dispatch","data":{"type":"focus","extensions":[]}}, and confirm that the connected clients receive it.

Checklist

• I've considered possible cross-platform impacts (Mac, Linux, Windows)
• I've considered possible documentation changes
• I've considered analytics changes to measure impact
• The change is user-facing — I've identified the correct bump type (patch for bug fixes · minor for new features · major for breaking changes) and added a changeset with pnpm changeset add