nest: Emitting an error event throws an exception

Bug Report

Current behaviour

If you emit an error event in a web socket gateway:

socket.emit('error', 'un-authorized');

it throws an unhandled exception like this:

UnhandledPromiseRejectionWarning: Error [ERR_UNHANDLED_ERROR]: Unhandled error. ('un-authorized')

The same thing happens even if we throw a WsException:

throw new WsException('un-authorized');

The error doesn’t get forwarded to the client. The client is set to listen to this error event, get the message and show it to the user.

Expected behavior

Forwarding the error event to the client which triggers the on error event.

Environment

Nest version: 6.7.1

For Tooling issues:

• Node version: 10.16.0
• Platform: Mac