MoleClient: handle unknown error codes

[yoursunny]

The code has a bug: if the server sends an error code other than -32601 and -32002, the client shows an unfriendly error: errorBuilder is not a function.

$ node ./main.js 
C:\Users\sunny\Documents\code\node-mole-rpc\MoleClient.js:197
        return errorBuilder(errorData);
               ^

TypeError: errorBuilder is not a function
    at MoleClient._makeErrorObject (C:\Users\sunny\Documents\code\node-mole-rpc\MoleClient.js:197:16)
    at MoleClient._processSingleCallResponse (C:\Users\sunny\Documents\code\node-mole-rpc\MoleClient.js:106:38)
    at MoleClient._processResponse (C:\Users\sunny\Documents\code\node-mole-rpc\MoleClient.js:88:18)
    at WebSocket.callback (C:\Users\sunny\Documents\code\mole-test\node_modules\←[4mmole-rpc-transport-ws←[24m\TransportClientWS.js:24:13)
    at WebSocket.onMessage (C:\Users\sunny\Documents\code\mole-test\node_modules\←[4mws←[24m\lib\event-target.js:125:16)  
←[90m    at WebSocket.emit (events.js:315:20)←[39m
    at Receiver.receiverOnMessage (C:\Users\sunny\Documents\code\mole-test\node_modules\←[4mws←[24m\lib\websocket.js:800:20)
←[90m    at Receiver.emit (events.js:315:20)←[39m
    at Receiver.dataMessage (C:\Users\sunny\Documents\code\mole-test\node_modules\←[4mws←[24m\lib\receiver.js:436:14)     
    at Receiver.getData (C:\Users\sunny\Documents\code\mole-test\node_modules\←[4mws←[24m\lib\receiver.js:366:17)

This patch fixes the bug by constructing a generic Error object with errorData.code and errorData.message.

---

To reproduce the bug:

client.js

const MoleClient = require('mole-rpc/MoleClient');
const TransportClientWS = require('mole-rpc-transport-ws/TransportClientWS');
const WebSocket = require('ws');

async function main() {
  const client = new MoleClient({
    requestTimeout: 1000,
    transport: new TransportClientWS({
      wsBuilder: () => new WebSocket(`ws://192.168.5.13:7000`, { protocol: "text" })
    })
  });

  try {
    const arg = {};
    const result = await client.callMethod("X.CreateError", arg);
    console.log(result);
  } catch (err) {
    console.error(err);
  }
}

main().then(console.log, console.error);

server.go

package main

import (
	"context"
	"errors"
	"log"
	"net/http"
	"net/rpc"

	"github.com/powerman/rpc-codec/jsonrpc2"
	"nhooyr.io/websocket"
)

type X struct{}

func (X) CreateError(args struct{}, res *int) error {
	return errors.New("server error")
}

func main() {
	rpc.Register(X{})

	fn := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		c, err := websocket.Accept(w, r, nil)
		if err != nil {
			log.Println(err)
			return
		}
		defer c.Close(websocket.StatusInternalError, "")
		jsonrpc2.ServeConn(websocket.NetConn(context.Background(), c, websocket.MessageText))
		c.Close(websocket.StatusNormalClosure, "")
	})

	err := http.ListenAndServe("0.0.0.0:7000", fn)
	log.Fatal(err)
}

Response sent by server:

{"jsonrpc":"2.0","id":"AayLg-OHP0","error":{"code":-32000,"message":"server error"}}

[yoursunny]

Hey @koorchik can you review and merge?

[yoursunny]

After a long time without action from the repository owner, I have decided to publish my patches in a fork: @yoursunny/mole-rpc.
If anyone else is affected from this bug, you can try my fork.

[justin0mcateer]

This issue will affect our ability to use as well. I've just been reviewing the code for our use and there are several 'robustness' issues that stick out, this being one of them....