Wrong title above 'add to project' state ("EDIT_DOCUMENT")

The title above the 'add to project' state is wrong. It shows a translation key as-is ("EDIT_DOCUMENT").

Steps to reproduce:

1. Start HAP enterprise
2. Navigate to Channels > Hippo Acceptance Project > Events
3. Select project 'q'
4. Click an 'edit content' button for a document that's not part of project 'q' yet.

Expected: the title of the right side panel is 'Document' (in small font) with the title of the document underneath.

Actual: the title of the right side panel is 'EDIT_DOCUMENT'.