core: fix url generate in ws conn

packages/hydrooj/package.json

@@ -1,6 +1,6 @@
 {
     "name": "hydrooj",
-    "version": "2.20.20",
+    "version": "2.20.21",
     "bin": "bin/hydrooj.js",
     "main": "dist/loader.js",
     "typings": "dist/loader.d.ts",

packages/hydrooj/src/service/server.ts

@@ -310,7 +310,7 @@ export class HandlerCommon {
         try {
             const { anchor } = args;
             if (args.domainId) name += '_with_domainId';
-            else if (this.domain?.host !== this.request.host && this.domainId !== 'system') {
+            else if ((!this.request.host || this.domain?.host !== this.request.host) && this.domainId !== 'system') {
                 name += '_with_domainId';
                 args.domainId = this.domainId;
             }