Concurrency issue: No error message when user edits deleted item

[helkv]

Testserver: qa imeji
Browser: ff
Version: 4.8.1 - build date 2020-02-05 11:46:22
User: default

No error message is shown if a user saves an edited item, which is deleted shortly before by another user.

Actions:

1. Login as user1
2. Login as user2 [parallel in another browser/session]
3. Open edit item view of an item (as user1) [user1 and user2 must have edit rights for the item]
4. Delete the edited item (as user2)
5. Save edited item (as user1)
6. Item is deleted but no error message is displayed!

[helkv]

There are many similar problems related to error messages for concurrency issues.
See #1182 for a list of all cases.