How to reproduce

• open cms
• open tag module
• Browse the tree
• select a tag
• click on "delete a tag"
• click ok to confirm the deletion
• click a second tine on "delete a tag" (button is available without tag selected)
• click ok

Actual behavior

• an error occured

Expected behavior

• After a tag is deleted, another tag or node should be selected
• or the buttons should not be available because nothing is selected after the first deletion.