judge: also fix for daemon

packages/hydrojudge/package.json

@@ -1,7 +1,7 @@
 {
     "name": "@hydrooj/hydrojudge",
     "bin": "bin/hydrojudge.js",
-    "version": "2.4.14",
+    "version": "2.4.15",
     "os": [
         "linux"
     ],

packages/hydrojudge/src/hosts/hydro.ts

@@ -195,7 +195,7 @@ export default class Hydro {
     async cacheOpen(domainId: string, pid: string, files: any[], next?) {
         const domainDir = path.join(getConfig('cache_dir'), this.config.host, domainId);
         const filePath = path.join(domainDir, pid); await fs.ensureDir(filePath);
-        if (!files.length) throw new SystemError('Problem data not found.');
+        if (!files?.length) throw new SystemError('Problem data not found.');
         let etags: Record<string, string> = {};
         try {
             etags = JSON.parse(fs.readFileSync(path.join(filePath, 'etags')).toString());