Why do I keep getting a read access violation? C++ - c++

Question

I keep running through the program and changing around pointers and I don't see what I am missing. I keep getting a read access violation on line 42 of the .cpp file and I am genuinely confused on how.
Here is the .cpp file
#include "Graph.h";
void Graph::insertEdge(int from, int to, int weight)
{
if (from <= size && to <= size)
{
bool leave = true;
EdgeNode* current = vertices[from].edgeHead;
while (leave)
{
if (from == current->adjVertex || current == nullptr) //Read access violation here
{
current->weight = weight;
if (current == nullptr)
{
current->adjVertex = to;
current->nextEdge = nullptr;
}
leave = false;
}
else
current = current->nextEdge;
}
}
}
and here is the .h file
#include "Vertex.h";
#include <fstream>;
using namespace std;
class Graph
{
static const int MAX_VERTICES = 101;
struct EdgeNode
{
int adjVertex = 0;
int weight = 0;
EdgeNode* nextEdge = nullptr;
};
struct VertexNode
{
EdgeNode* edgeHead = nullptr;
Vertex* data = nullptr;
};
struct Table
{
bool visited;
int dist;
int path;
};
public:
void buildGraph(ifstream& in);
void insertEdge(int from, int to, int weight);
void removeEdge(int beginning, int end);
void findShortestPath();
void displayAll();
void display(int begin, int end);
private:
int size;
VertexNode vertices[MAX_VERTICES];
Table T[MAX_VERTICES][MAX_VERTICES];
};
I've been on this problem for multiple hours now and I can't seem to find the issue.

Answer 1

Probably instead of
if (from == current->adjVertex || current == nullptr)
you should first ensure the pointer is not null before dereferencing it.
if (current == nullptr || from == current->adjVertex)
then if current is null, the right-hand side of || operator won't be run.
HOWEVER, you will still have a problem because you also dereference current->weight inside the if-statement, even if current is null.