Viewing the rejected requests gives an error

Steps to reproduce:

1. Login as author
2. Go to a document
3. Make some changes
4. Login as admin
5. Go to the document from step 2
6. Reject the document
7. Login as author and go to document from step 2
8. Select Requests -> Show rejected requests

Expected result:

The rejected requests are shown

Actual result:

The rejected requests are not shown. See error in screenshot