refactor: rename ERROR to CONNECT_ERROR

The meaning is not modified: this packet type is still used by the
server when the connection to a namespace is refused.

Breaking change: the Socket instance will now emit a "connect_error"
event instead of "error" (which is not a reserved event anymore)

```js
// before
socket.on("error", () => {});

// after
socket.on("connect_error", () => {});
```

lib/socket.ts

@@ -20,9 +20,9 @@ export interface SocketOptions {
 
 const RESERVED_EVENTS = {
   connect: 1,
+  connect_error: 1,
   disconnect: 1,
   disconnecting: 1,
-  error: 1,
   // EventEmitter reserved events: https://nodejs.org/api/events.html#events_event_newlistener
   newListener: 1,
   removeListener: 1,
@@ -220,10 +220,8 @@ export class Socket extends Emitter {
    */
   private onpacket(packet) {
     const sameNamespace = packet.nsp === this.nsp;
-    const rootNamespaceError =
-      packet.type === PacketType.ERROR && packet.nsp === "/";
 
-    if (!sameNamespace && !rootNamespaceError) return;
+    if (!sameNamespace) return;
 
     switch (packet.type) {
       case PacketType.CONNECT:
@@ -251,8 +249,8 @@ export class Socket extends Emitter {
         this.ondisconnect();
         break;
 
-      case PacketType.ERROR:
-        super.emit("error", packet.data);
+      case PacketType.CONNECT_ERROR:
+        super.emit("connect_error", packet.data);
         break;
     }
   }

package.json

@@ -34,7 +34,7 @@
     "debug": "~4.1.0",
     "engine.io-client": "~4.0.0",
     "parseuri": "0.0.6",
-    "socket.io-parser": "4.0.1-rc2"
+    "socket.io-parser": "4.0.1-rc3"
   },
   "devDependencies": {
     "@babel/core": "^7.11.6",

test/socket.ts

@@ -176,7 +176,7 @@ describe("socket", function () {
 
   it("should fire an error event on middleware failure from custom namespace", (done) => {
     const socket = io("/no", { forceNew: true });
-    socket.on("error", (err) => {
+    socket.on("connect_error", (err) => {
       expect(err).to.eql("Auth failed (custom namespace)");
       socket.disconnect();
       done();