Message navigation is broken when deleted messages are hidden

[brichet]

Description

When the property showDeleted is unchecked in settings and some messages are deleted in the chat, the message navigation is broken (cannot jump to last message anymore).

Reproduce

• delete a message with the trash in the message toolbar
• uncheck the showDeleted option in settings
• reload the application
• the down arrow to jump to last message is not working anymore

Expected behavior

The messages navigation to work.

Context

The message navigation and unread messages use the message in viewport.
When the deleted messages are not shown, they are not rendered at all, an are never in the viewport.
Therefore, the messages are always unread and the navigation is broken.