+ fixed 2 cast errors I have spotted
Fix to ensure T29391. Can be removed as soon as T28524 is solved
and the new MultiLabelSegmentation class is in place, this
check can be removed, as Segmentation won't be confused with
simple images anymore.
Test Plan: Try to save segmention. Only nrrd (and dicom if input image was dicom) is available.
Reviewers: O1 MITK Reviewer Group I, kalali
Reviewed By: O1 MITK Reviewer Group I, kalali
Maniphest Tasks: T29391
Differential Revision: https://phabricator.mitk.org/D761