Question about WebSocketServer.onError()

[Steelight]

WebSocketServer.onError() is sometimes raised with conn == null. I originally assumed this means that the error is on the server socket itself, but I see this is not always the case. What is the correct way to distinguish error on the server from errors on accepted WebSockets? What is the correct way to handle error events on null sockets?

[Davidiusdadi]

There are 3 cases in which onError() will be called with conn == null

1. If the server can not bind the ServerSocket on startup // ex == IOException
2. on uncaught RuntimeExceptions
3. If an IOException occures on a channel which has not yet been assigned to a websocket

[Steelight]

Thank you!