vtkContourFilter crashes on vtkPolyData input when using a ScalarTree
See https://gitlab.kitware.com/vtk/vtk/blob/54f33fc141533c302724ef3c7070828dd629cdef/Filters/Core/vtkContourFilter.cxx#L618 and https://gitlab.kitware.com/vtk/vtk/-/blob/54f33fc141533c302724ef3c7070828dd629cdef/Common/ExecutionModel/vtkSimpleScalarTree.cxx#L220
The ScalarTree is not assigned input data. As a result the ScalarTree cannot build a Tree and InitTraversal will attempt to dereference a nullptr.
A workaround is to call vtkContourFilter::GetScalarTree()->SetDataSet() before the execution of vtkContourFilter