Ca: bugfix with nans in the track fit
A fix for the redmine issue: https://redmine.cbm.gsi.de/issues/2981#change-14601
Edit for Redmine linking: Refs #2981
A fix for the redmine issue: https://redmine.cbm.gsi.de/issues/2981#change-14601
Edit for Redmine linking: Refs #2981