It's possible to generate a 500 Internal Server Error when trying to save a Draft of a Content that was not yet published.

Steps to reproduce:
1. Go to Content -> Content Structure
2. Create a content item
3. Fill out the required fields (if needed)
4. Click "Save"

Result:
500 Internal Server Error: Argument 'Location' is invalid: Provided location does not belong to selected content

Expected result:
Draft is saved?

PROBABLY RELATED
When a Draft (that has not been published yet) is sent for Review to a user, trying to view it from notifications panel results in a 404 error (Error: Could not find 'location' with identifier '0').