[BUGFIX] Select first element in tree when deleting selected node

This patch fixes a bug which occured when deleting a currently selected
node. After deleting this node the first element of the tree is
displayed.

Releases: master
Resolves: #85431
Change-Id: I64cd7c4ebd8415a2c261da3f62f8e412575b0075
Reviewed-on: https://review.typo3.org/57791


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Łukasz Uznański <l.uznanski@macopedia.pl>
Tested-by: Łukasz Uznański <l.uznanski@macopedia.pl>
Reviewed-by: Joerg Kummer <typo3@enobe.de>
Tested-by: Joerg Kummer <typo3@enobe.de>
Reviewed-by: Andreas Fernandez <a.fernandez@scripting-base.de>
Tested-by: Andreas Fernandez <a.fernandez@scripting-base.de>
Reviewed-by: Tymoteusz Motylewski <t.motylewski@gmail.com>
Tested-by: Tymoteusz Motylewski <t.motylewski@gmail.com>