Perform IntTools_FaceFace core dump

hi everyone, i use occ7.6， When I use these two faces as input to execute IntTools_FaceFace, the program will dump

the surface type is Geom_ConicalSurface

debug program this core dump in ProjLib_ComputeApprox.cpp MC.Degree() there

    // on essaie de rendre la courbe au moins C1
      Convert_CompBezierCurves2dToBSplineCurve2d Conv;

      Standard_Real Tol3d,Tol2d;
      for (i = 1; i <= NbCurves; i++) {
          Fit.Error(i,Tol3d, Tol2d);
              aNewTol2d = Max(aNewTol2d, Tol2d);
          AppParCurves_MultiCurve MC = Fit.Value( i);       //Charge la Ieme Curve
          TColgp_Array1OfPnt2d Poles2d( 1, MC.Degree() + 1);//Recupere les poles
          MC.Curve(1, Poles2d);        
          Conv.AddCurve(Poles2d);
 }

find MC.tabPoint is null.

How to limit this situation, before Perform IntTools_FaceFace, thanks