Error when selecting notification item with keyboard

Description

Step to reproduce:

1. Open a notification list.
2. Press the arrow up/down key.

• Note: The problem only occurs if there's no notification at the start, then a new notification comes in.

Expected:
You can select a list item.

Actual:
Error in the console.

Note: A similar problem is related with blocks list. If a folder has no blocks and a user clicks the list of blocks, the same error is thrown.