Add checks/Exceptions to MAP if TotalSegmentator contours are empty

Currently, the MAP outputs a PDF and an RT Struct DICOM even if the TotalSegmentator operator doesn't run. Need to decide the MAP failure behaviour – expect we don't want it to output anything.

No files, tests, or entry points are named. Start by locating the MAP output generation and the handling of empty TotalSegmentator contours, then establish the desired failure behavior before changing it; done means the MAP does not produce the PDF or RT Struct DICOM when the operator does not run.

Written by the indexing model from the issue text.