Ignore gone exceptions

[hansottowirtz]

It's possible that an API Gateway subscription is already closed by the client when trying to publish. E.g.:

• The client opens a connection, the connection and subscription are stored in DynamoDB.
• The client closes the connection, which might only be handled 200ms later because of a cold start.
• A few milliseconds after closing, the server wants to publish to a subscription. The connection is not yet deleted from DynamoDB so the query returns the closed connection.
• The API Gateway Management API throws a "GoneException" because the connection is closed.

This PR adds a catch block that ignores a GoneException.

This will need further verification.

[reconbot]

I wonder if it's better to go ahead and delete the connection from ddb too. This patch works fine to overcome the runtime race condition that results in a needless error. I'm happy to land it if you don't want it to be a draft.

[izidormaklary]

It would definitely make more sense to delete the connections and the subscriptions if they are gone.

.catch(async (err) => {
    if (err?.statusCode !== 410) throw err;
    await server.models.connection.delete({ id: ConnectionId });
    await server.models.subscription.delete({ id: `${ConnectionId}|${message.id}` });
    console.warn('Connection already closed at API Gateway, deleting connection and related subscription');
};

Although this still leaves the subscriptions in the ddb that are related to the connection but aren't posted to.

[reconbot]

Well the disconnect event will take care of them, and last but not least the TTL will do the final cleanup.