fix: 修复账号搜索 5xx (#6413)

Co-authored-by: ibuler <ibuler@qq.com>
Co-authored-by: Jiangjie.Bai <32935519+BaiJiangJie@users.noreply.github.com>

apps/assets/models/authbook.py

@@ -63,6 +63,12 @@ class AuthBook(BaseUser, AbsConnectivity):
     def username_display(self):
         return self.get_or_systemuser_attr('username') or '*'
 
+    @property
+    def systemuser_display(self):
+        if not self.systemuser:
+            return ''
+        return str(self.systemuser)
+
     @property
     def smart_name(self):
         username = self.username_display