Need a way to detect connection errors of websocket

[bynil]

The error that occurred in stream reading is ignored now.

ethgo/jsonrpc/transport/websocket.go

Lines 91 to 98 in f671bdb

	var err error
	buf, err = s.codec.Read(buf[:0])
	if err != nil {
	if !s.isClosed() {
	// log error
	}
	return
	}

When we subscribe an event and get no messages, we can not know if the underlying websocket connection is healthy(the network may be down).

Maybe we should add a callback for all unexpected connection errors.

eg.
Subscribe(method string, callback func(b []byte), errHandler func(err error)) (func() error, error)

[ferranbt]

The proposal sounds okay. Can you share the error you get from the stream?

[bynil]

The proposal sounds okay. Can you share the error you get from the stream?

I subscribed for new heads:

	events := make(chan []byte, 10000)
	closeFn, err = WsRPC.Subscribe("newHeads", func(b []byte) {
		events <- b
	})

Then disable the network, will get a CloseError from gorilla/websocket:
https://github.com/gorilla/websocket/blob/af47554f343b4675b30172ac301638d350db34a5/conn.go#L105