Clean up thrown error on disconnect

[andyrichardson]

Changes

• Calls disconnect message handler on thrown errors
• Ensures full cleanup of server side connection close

Clean clean-up

Promise.allSettled ensures that as much cleanup as possible is done - even if some fails.

This method might be a requirement for here also where the first thrown error would potentially cause the lambda to shutdown before other (potentially succeeding) promises can be resolved.

Something like this could work

try {
  await Promise.allSettled([
    Promise.resolve("Resolved!"),
    Promise.reject("Rejected!")
  ]).then((r) =>
    r.forEach(({ status, reason }) => {
      if (status === "rejected") {
        throw reason;
      }
    })
  );
} catch (err) {
  console.log(err);
}