Fixed reason for crash by switching to check the nodes set for the model.
Summary: Signed-off-by: Ralf Floca <r.floca@dkfz-heidelberg.de>
Test Plan: Review and test in UI
Reviewers: kalali, kislinsk
Reviewed By: kislinsk
Maniphest Tasks: T27192
Differential Revision: https://phabricator.mitk.org/D260