Fuzzy boolean operations give access violation under certain circumstances

Occurs in OCCT 7.4.0. Respective Code is unchanged in OCCT 7.6.0:

happens if myUparams.IsNull() in

void IntTools_SurfaceRangeLocalizeData::SetFrame(const Standard_Real theUMin,
                         const Standard_Real theUMax,
                         const Standard_Real theVMin,
                         const Standard_Real theVMax)
{
  myUIndMin   = 0;
  myUIndMax   = 0;
  myVIndMin   = 0;
  myVIndMax   = 0;

  if (myUParams.IsNull() || myVParams.IsNull()) {
    return;
  }

The routine is used in

IntTools\IntTools_BeanFaceIntersector.cxx

void BuildBox(const Handle(Geom_BSplineSurface)       &theSurf,
      const Standard_Real                      theFirstU,
      const Standard_Real                      theLastU,
      const Standard_Real                      theFirstV,
      const Standard_Real                      theLastV,
            IntTools_SurfaceRangeLocalizeData &theSurfaceData,
              Bnd_Box                           &theBox)
{
  Standard_Integer i;
  Standard_Integer j;
  Standard_Integer aNbUPnts;
  Standard_Integer aNbVPnts;
  Standard_Real    aParam;
  gp_Pnt           aPnt;

  theSurfaceData.SetFrame(theFirstU, theLastU, theFirstV, theLastV);
  aNbUPnts = theSurfaceData.GetNBUPointsInFrame();
  aNbVPnts = theSurfaceData.GetNBVPointsInFrame();

  // Add corner points.
  theSurf->D0(theFirstU, theFirstV, aPnt);
  theBox.Add(aPnt);
  theSurf->D0(theLastU,  theFirstV, aPnt);
  theBox.Add(aPnt);
  theSurf->D0(theFirstU, theLastV, aPnt);
  theBox.Add(aPnt);
  theSurf->D0(theLastU,  theLastV, aPnt);
  theBox.Add(aPnt);

  for (i = 1; i <= aNbUPnts; i++) {
    // Add top and bottom points.
    aParam = theSurfaceData.GetUParamInFrame(i);

and the access violation occurs then in GetUParamInFrame(i), because e.g. aNbUPnts = 1, because:

inline Standard_Integer IntTools_SurfaceRangeLocalizeData::
                                 GetNBUPointsInFrame() const
{
  return myUIndMax - myUIndMin + 1;
}

0-0+1 = 1