fix-修复任务站内信用户发送错误

app/Services/Notification/ActionBrowser/TaskNotification.php

@@ -8,8 +8,8 @@ class TaskNotification extends ActionBrowserNotificationAbstract
 {
     protected function userIDs(): array
     {
-        $assignArray=$this->object->assign;
-        $mailtoArray=$this->object->mailto;
+        $assignArray=isset($this->object->assign)?$this->object->assign:[];
+        $mailtoArray=isset($this->object->mailto)?$this->object->mailto:[];
         return (!empty($assignArray) || !empty($mailtoArray)) ? array_unique(array_merge($assignArray, $mailtoArray)) : [];
     }
 }