Fix for subprotocol: some browsers reject empty string

[cxa]

See #133 (comment)

[haraldsegliens]

@phoboslab can you, please, merge this. The problem is still present. See: https://stackoverflow.com/questions/73591020/jsmpeg-in-chrome-cannot-read-websocket-stream-served-by-spring-webflux.

But the provided change doesn't work in Chrome, because of a error: DOMException: Failed to construct 'WebSocket': The subprotocol '' is invalid.

The change that works in Chrome is as follows:

if(this.options.protocols) {
   this.socket = new WebSocket(this.url, this.options.protocols);
} else {
    this.socket = new WebSocket(this.url);
}

[phoboslab]

Thanks for the info and your patience! :)

[haraldsegliens]

Thank you :)