Steps to reproduce
- Create a display page template for an item type that doesn't have form variations (see note below)
- Add a fragment with an editable field (for example Heading)
- Click on the fragment and click again to focus the editable field.
- In the side panel go to the mapping tab.
The Source field shows a default value of "unknown-variation(0)"
The Source field shows a default value with a human-friendly name of the item type.
This issue can currently only be reproduced by developing support for a custom item type. I found it while developing an example.
While this could also happen to Blogs Entry, it doesn't because as of today it still has an InfoDisplayContributor implementation active which makes the code avoid the problem.