diff --git a/packages/hydrooj/package.json b/packages/hydrooj/package.json
index 01a3496cf..983ebfaaa 100644
--- a/packages/hydrooj/package.json
+++ b/packages/hydrooj/package.json
@@ -1,6 +1,6 @@
 {
     "name": "hydrooj",
-    "version": "2.23.28",
+    "version": "2.23.29",
     "bin": "bin/hydrooj.js",
     "main": "dist/loader.js",
     "typings": "dist/loader.d.ts",
diff --git a/packages/hydrooj/src/model/user.ts b/packages/hydrooj/src/model/user.ts
index d034cda04..0c4e076bd 100644
--- a/packages/hydrooj/src/model/user.ts
+++ b/packages/hydrooj/src/model/user.ts
@@ -200,7 +200,7 @@ class UserModel {
         const salt = String.random();
         if (!uid) {
             const [udoc] = await coll.find({}).sort({ _id: -1 }).limit(1).toArray();
-            uid = Math.max((udoc._id || 0) + 1, 2);
+            uid = Math.max((udoc?._id || 0) + 1, 2);
         }
         try {
             await coll.insertOne({
diff --git a/packages/ui-default/components/cmeditor/cmeditor.styl b/packages/ui-default/components/cmeditor/cmeditor.styl
index d28d5640b..6b1f79541 100644
--- a/packages/ui-default/components/cmeditor/cmeditor.styl
+++ b/packages/ui-default/components/cmeditor/cmeditor.styl
@@ -1,2 +1,5 @@
 .vditor
   margin-bottom: rem(10px)
+
+.vditor-preview__action
+  display: none
diff --git a/packages/ui-default/package.json b/packages/ui-default/package.json
index d39483a81..aa2686a93 100644
--- a/packages/ui-default/package.json
+++ b/packages/ui-default/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@hydrooj/ui-default",
-  "version": "4.6.20",
+  "version": "4.6.21",
   "author": "undefined <i@undefined.moe>",
   "license": "AGPL-3.0",
   "main": "hydro.js",