Cannot delete a 'relevance characteristic' in a drag&drop component

The original client issue:

We are encountering a bug with the Targeting & Relevance module in combination with the Channel Manager catalog components.

reproduction path

• Add one or more characteristics in the relevance module (custom made characteristics or out-of-the-box characteristics, doesn't matter).
• Go to the Channel Manager, add / edit a drag&drop component and click '+ Add targeting configuration' to add a new characteristics config.
• Click 'Add characteristic' and select one.
• Click 'Save'
• Close the popup.
• Click 'Save & Close' in the Channel Manager.
• Click 'Publish my changes'
• Now, edit the channel again. Open the drag&drop component popup.
• Go to that target configuration tab and click 'Delete'.
• Note that nothing happens and an error is thrown in the logs / console (see attachment)

note:
there's a workaround to delete the characteristic: simply click 'Save' in the popup. Then, try the 'Delete' button again.