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.
Kristian Bendiksen
08b998ac4c