Access violation in C++

@freedompeace

its from the file loader function which (load()) and when this function tries to call the Triangle function
Triangle::Triangle(
const Vertex *vertexA,
const Vertex *vertexB,
const Vertex *vertexC,
unsigned r, unsigned g, unsigned b,
bool twosided , bool triNormalProvided,
Float3 triNormal)
:
_vertexA(vertexA), _vertexB(vertexB), _vertexC(vertexC),

centroid((vertexA->X + vertexB->X + vertexC->X)/3.0f,
(vertexA->Y + vertexB->Y + vertexC->Y)/3.0f,
(vertexA->Z + vertexB->Z + vertexC->Z)/3.0f),

_colorf((float)r,(float)g,(float)b), // For use in all other cases
_color(SDL_MapRGB(Screen::_surface->format, r,g,b)), // For use with DrawPixel
_twoSided(twosided),
_bottom(FLT_MAX,FLT_MAX, FLT_MAX), // Will be updated after centering in Loader
_top(-FLT_MAX, -FLT_MAX,-FLT_MAX) // Will be updated after centering in Loader
{
if (!triNormalProvided)
{
n = Float3((vertexA->n.X + vertexB->n.X + vertexC->n.X)/3.0f,
(vertexA->n.Y + vertexB->n.Y + vertexC->n.Y)/3.0f,
(vertexA->n.Z + vertexB->n.Z + vertexC->n.Z)/3.0f);
n.Normalize();
}
else {n = triNormal;}
}