Remove assert from GetAttributeValue(idx) if idx out of range.
Remove assert from GetAttributeValue(idx) if idx out of range.

Instead, an invalid value is returned if idx is out of range.
I'm leaving the asserts in place for the Set methods.

hendradarwin/vtk-dicom,dgobbi/vtk-dicom,hendradarwin/vtk-dicom,dgobbi/vtk-dicom,hendradarwin/vtk-dicom,dgobbi/vtk-dicom