  Dual_Project( TT_ExecContext  exc,
                FT_Pos          dx,
                FT_Pos          dy )
  {
    return TT_DotFix14( dx, dy,
                        exc->GS.dualVector.x,
                        exc->GS.dualVector.y );
  }

The product dereferences a pointer that it expects to be valid but is NULL.