What is the WebSocket error on status 200?

On a WebSocket connection you want a 101 Switching Protocols status response.
Getting a 200 status response, probably means that the request didn't reach your WebSocket Handler.

I would also look into the dev-tools, and check if the response has any WebSocket handshake headers.
If it has, I would assume it's a problem with the module. Otherwise it's probably your configuration.