User receives error screen, because of not found task

Please see linked TS-issue.

The cause is this trace in PHP:

Exception: ZfExtended_Models_Entity_NotFoundException
Level: ERROR
Errorcode: E9999
Message: Task Entity Not Found: Key: editor_Models_Task#taskGuid; Value:

Domain: core
Version: 5.6.4
File (Line): /webs/instance-1031/library/ZfExtended/Models/Entity/Abstract.php (213)
User: xyz (

)
Request: GET /editor
Trace:

#0 /webs/instance-1031/application/modules/editor/Models/Task.php(245): ZfExtended_Models_Entity_Abstract->notFound()
#1 /webs/instance-1031/application/modules/editor/Controllers/IndexController.php(445): editor_Models_Task->loadByTaskGuid()
#2 /webs/instance-1031/application/modules/editor/Controllers/IndexController.php(375): Editor_IndexController->setJsAppData()
#3 /webs/instance-1031/application/modules/editor/Controllers/IndexController.php(147): Editor_IndexController->setJsVarsInView()
#4 /webs/instance-1031/vendor/shardj/zf1-future/library/Zend/Controller/Action.php(516): Editor_IndexController->indexAction()
#5 /webs/instance-1031/vendor/shardj/zf1-future/library/Zend/Controller/Dispatcher/Standard.php(308): Zend_Controller_Action->dispatch()
#6 /webs/instance-1031/vendor/shardj/zf1-future/library/Zend/Controller/Front.php(954): Zend_Controller_Dispatcher_Standard->dispatch()
#7 /webs/instance-1031/vendor/shardj/zf1-future/library/Zend/Application/Bootstrap/Bootstrap.php(105): Zend_Controller_Front->dispatch()
#8 /webs/instance-1031/vendor/shardj/zf1-future/library/Zend/Application.php(384): Zend_Application_Bootstrap_Bootstrap->run()
#9 /webs/instance-1031/library/ZfExtended/Application.php(47): Zend_Application->run()
#10 /webs/instance-1031/library/ZfExtended/BaseIndex.php(149): ZfExtended_Application->run()
#11 /webs/instance-1031/public/index.php(35): ZfExtended_BaseIndex->startApplication()
#12

To reproduce

• open task for editing with one user
• close the tab/browser (here logout on windows close must be disabled)
• open translate5 with different user in different browser and remove this task
• try to login with the first user and you will get the error screen

The problem is after deleting the task, the taskGuid still exist in the session table for all users which are editing the task