Resolves: fdo#80101 inserting non-chart as chart -> unhandled exception

Change-Id: I4d5438292d9a5c49f1336304ebd3dc4e155dd212
(cherry picked from commit 76d4db3181dfd1524620377bb12a8e0332ae8ab0)
Reviewed-on: https://gerrit.libreoffice.org/11833
Reviewed-by: Eike Rathke <erack@redhat.com>
Tested-by: Eike Rathke <erack@redhat.com>