fix websocket unpacking (#3301)

src/WebSocket.js

@@ -6,9 +6,13 @@ try {
   if (!erlpack.pack) erlpack = null;
 } catch (err) {} // eslint-disable-line no-empty
 
+let TextDecoder;
+
 if (browser) {
+  TextDecoder = window.TextDecoder; // eslint-disable-line no-undef
   exports.WebSocket = window.WebSocket; // eslint-disable-line no-undef
 } else {
+  TextDecoder = require('util').TextDecoder;
   try {
     exports.WebSocket = require('@discordjs/uws');
   } catch (err) {
@@ -16,12 +20,19 @@ if (browser) {
   }
 }
 
+const ab = new TextDecoder();
+
 exports.encoding = erlpack ? 'etf' : 'json';
 
 exports.pack = erlpack ? erlpack.pack : JSON.stringify;
 
 exports.unpack = data => {
-  if (!erlpack || data[0] === '{') return JSON.parse(data);
+  if (exports.encoding === 'json') {
+    if (typeof data !== 'string') {
+      data = ab.decode(data);
+    }
+    return JSON.parse(data);
+  }
   if (!Buffer.isBuffer(data)) data = Buffer.from(new Uint8Array(data));
   return erlpack.unpack(data);
 };

src/client/websocket/WebSocketShard.js

@@ -3,16 +3,12 @@
 const EventEmitter = require('events');
 const WebSocket = require('../../WebSocket');
 const { Status, Events, ShardEvents, OPCodes, WSEvents } = require('../../util/Constants');
-const { TextDecoder } = require('util');
 
 let zstd;
-let decoder;
-
 let zlib;
 
 try {
   zstd = require('zucc');
-  decoder = new TextDecoder('utf8');
 } catch (e) {
   try {
     zlib = require('zlib-sync');
@@ -259,8 +255,7 @@ class WebSocketShard extends EventEmitter {
   onMessage({ data }) {
     let raw;
     if (zstd) {
-      const ab = this.inflate.decompress(new Uint8Array(data).buffer);
+      raw = this.inflate.decompress(new Uint8Array(data).buffer);
-      raw = decoder.decode(ab);
     } else {
       if (data instanceof ArrayBuffer) data = new Uint8Array(data);
       const l = data.length;