core: bug fix

packages/hydrooj/package.json

@@ -1,6 +1,6 @@
 {
     "name": "hydrooj",
-    "version": "3.10.0",
+    "version": "3.10.1",
     "bin": "bin/hydrooj.js",
     "main": "src/loader",
     "module": "src/loader",

packages/hydrooj/src/handler/problem.ts

@@ -172,7 +172,7 @@ export class ProblemMainHandler extends ProblemHandler {
             ? [[], 0, 0]
             : await problem.list(
                 domainId, query,
-                sort.length ? 1 : page, system.get('pagination.problem'),
+                sort?.length ? 1 : page, system.get('pagination.problem'),
                 undefined, this.user._id,
             );
         if (total) {