#13922 PolygonFilter: Guard K index against per-grid cellCountK

The K layer returned by findEclipseKLayer is computed against one grid
(usually the main grid), but updateCellsForEclipse then forwards it to
every grid including LGRs whose cellCountK can be smaller. Inside
updateCellsKIndexEclipse the unguarded cellIndexFromIJKUnguarded call
combined with the bounds-unchecked cell() accessor produced an
out-of-range cell whose corner indices crashed RigCell::center() and
cellCornerVertices.

Fixes #13922.

ApplicationLibCode/ProjectDataModel/CellFilters/RimPolygonFilter.cpp

@@ -486,6 +486,8 @@ void RimPolygonFilter::updateCellsKIndexEclipse( const std::vector<cvf::Vec3d>&
 {
     const int gIdx = static_cast<int>( grid->gridIndex() );
 
+    if ( K < 0 || static_cast<size_t>( K ) >= grid->cellCountK() ) return;
+
     std::list<size_t> foundCells;
     const bool        closedPolygon = isPolygonClosed();
     const bool        singlePoint   = ( points.size() == 1 );