Describe the bug
When I press the 'delete' key on an empty list item, the item below the empty one gets merged with the one above.

A gif demo:

To Reproduce
Steps to reproduce the behavior:

1. Make a new list gutenberg block
2. Add some items
3. Make one of the items empty (no text, but still with a number / bullet)
4. Put cursor at the empty list item
5. Press 'delete' on your keyboard
6. See the two items around the empty list item merged

Expected behavior

Starting from this list:

1. Apples
2. Oranges
3. 
4. Limes
5. Lemons

I expected to see this after pressing 'delete' on item 3:

1. Apples
2. Oranges
4. Limes
5. Lemons