If the object doesn't exist or version doesn't exist, the cronjob will delete the process. But the item still approvable by the approver. I think deleting the item underground(in cronjob) is not a good solution because the user doesn't know.

The improvement might be: when he/she opens the workflow message, give a message to the approver that the process doesn't exist and one button for removing this message(also the item).

Related issues: http://issues.ez.no/IssueView.php?Id=6380

Steps to reproduce

Haven't test these steps, just show the basic meaning.
1. create a workflow with an approval event (admin can approve)
2. create a trigger before publish with 1)
3. editor(who can't bypass workflow) edits an article, publish it.(it will be sent to the approval)
4. admin deletes the article
5. run cronjob
6. checks admin collaboration inbox, it's still approvable.