#14906: Fix crash drawing seismic surface intersection lines for empty sections

Crash signature 69f8ebe0f20e.

RivSeismicSectionPartMgr::appendSurfaceIntersectionLines reads texturePart.rect[0] and rect[1] without a size check. texturedSection() clears rect and returns early when the section has no geometry, so the read is out of range.

Skip parts with fewer than two corner points.

Call stack:
[3] cvf::Vector3<double>::operator=(cvf::Vector3<double> const&) at ResInsight/Fwk/VizFwk/LibCore/cvfVector3.inl:140
[4] RimSeismicSectionCollection::appendPartsToModel(Rim3dView*, cvf::ModelBasicList*, caf::DisplayCoordTransform*, cvf::BoundingBox const&) at ResInsight/ApplicationLibCode/ProjectDataModel/Seismic/RimSeismicSectionCollection.cpp:183
[5] RimGeoMechView::onCreateDisplayModel() at ResInsight/ApplicationLibCode/ProjectDataModel/GeoMech/RimGeoMechView.cpp:322
[6] Rim3dView::createDisplayModelAndRedraw() at ResInsight/ApplicationLibCode/ProjectDataModel/Rim3dView.cpp:718
[7] RiaViewRedrawScheduler::updateAndRedrawScheduledViews() at ResInsight/ApplicationLibCode/Application/RiaViewRedrawScheduler.cpp:93
[12] RiaGuiApplication::notify(QObject*, QEvent*) at ResInsight/ApplicationLibCode/Application/RiaGuiApplication.cpp:1828
[22] main at ResInsight/ApplicationExeCode/RiaMain.cpp:267
[23] __libc_start_main at :0

ApplicationLibCode/ModelVisualization/Seismic/RivSeismicSectionPartMgr.cpp

@@ -222,6 +222,7 @@ void RivSeismicSectionPartMgr::appendSurfaceIntersectionLines( cvf::ModelBasicLi
         for ( int i = 0; i < texSection->partsCount(); i++ )
         {
             const auto& texturePart = texSection->part( i );
+            if ( texturePart.rect.size() < 2 ) continue;
 
             // Each part of the seismic section is a rectangle, use two corners of the rectangle to create a polyline
             std::vector<cvf::Vec3d> polyLineForSection = { texturePart.rect[0], texturePart.rect[1] };