fix(account middleware): 使用了未定义的变量。

src/commons/middleware/account.middleware.ts

@@ -11,7 +11,7 @@ export class AccountMiddleware implements NestMiddleware {
   async use(req: any, res: any, next: () => void) {
     const authPayload = req.header('authorization') ?? '';
     if (!authPayload) {
-      req.user = req.session.user;
+      req.user = req.session?.user;
       next();
       return;
     }