Resolves: fdo#79130 Crash in DomainMapper_Impl::CloseFieldCommand

Change-Id: Ia59e0c79ec7f2066891b78657559f41eaeb80a09
(cherry picked from commit a392a1deb0bb55f39f0232f9b3df8ad9ac9062af)
Reviewed-on: https://gerrit.libreoffice.org/11665
Reviewed-by: Miklos Vajna <vmiklos@collabora.co.uk>
Tested-by: Miklos Vajna <vmiklos@collabora.co.uk>