core: sockjs: change close code to 4000

packages/hydrooj/package.json

@@ -1,6 +1,6 @@
 {
     "name": "hydrooj",
-    "version": "2.18.2",
+    "version": "2.18.3",
     "bin": "bin/hydrooj.js",
     "main": "dist/loader.js",
     "typings": "dist/loader.d.ts",

packages/hydrooj/src/service/server.ts

@@ -702,7 +702,7 @@ export class ConnectionHandler extends HandlerCommon {
                 params: err.params || [],
             },
         });
-        this.close(1001, err.toString());
+        this.close(4000, err.toString());
     }
 
     async getSession(cookieHeader: string) {