Dynamic List <malloc.h> free triggered a breakpoint - C Programming - c

Question

Could someone help me with this one. I'm making BFS algorithm in C programming language, with help of dynamic lists.
This is my code.
// ConsoleApplication3.cpp : Defines the entry point for the console application.
//
#include "stdafx.h"
#include <malloc.h>
#define n 6
typedef struct field
{
int x;
int y;
int dist;
struct field *next;
}Field;
// Get row and column number of 4 neighbours
int rows[] = { -1, 0, 0, 1 };
int cols[] = { 0, -1, 1, 0 };
Field *addToEnd(Field *lst, Field field)
{
Field *newField = (Field*)malloc(sizeof Field);
newField = &field;
newField->next = NULL;
if (!lst)
return newField;
else
{
Field *current;
for (current = lst; current->next; current = current->next);
current->next = newField;
return lst;
}
}
// Check if field is/isn't out of range
bool isValid(int row, int col)
{
return (row >= 0) && (row < n) && (col >= 0) && (col < n);
}
int BFS(int mat[][n], Field source, Field destination)
{
bool visited[n][n];
memset(visited, false, sizeof visited);
// Mark the source field as visited
visited[source.x][source.y] = true;
// Create dynamic list
Field *lst = NULL;
source.dist = 0;
// Adding the source field to the list
lst = addToEnd(lst, source);
while (lst)
{
// Getting first element in the list
Field current = *lst;
// If destination is reached then end function
if (current.x == destination.x && current.y == destination.y)
return current.dist;
// Delete first element of the list
Field *toDelete;
toDelete = lst;
lst = lst->next;
free(toDelete);
for (int i = 0; i < 4; i++)
{
int row = current.x + rows[i];
int col = current.y + cols[i];
// If adjacent field is valid, has path and isn't visited add it to the list
if (isValid(row, col) && mat[row][col] == 0 && !visited[row][col])
{
visited[row][col] = true;
Field adjField = { row, col, current.dist + 1 };
lst = addToEnd(lst, adjField);
}
}
}
// Return -1 if destination can't be reached
return -1;
}
int main()
{
int mat[n][n] =
{
{ 0, 0, 0, 0, 0, 0 },
{ 0, 1, 1, 1, 1, 0 },
{ 0, 1, 0, 0, 0, 0 },
{ 0, 0, 0, 1, 1, 0 },
{ 0, 1, 0, 0, 0, 0 },
{ 0, 0, 0, 1, 1, 0 }
};
Field start = { 1, 0 }, end = { 5, 5 };
int number = BFS(mat, start, end);
if (number != -1)
printf("%d\n", number);
else
printf("Destination can't be reached\n");
return 0;
}
Everything except part of code which need to delete first element of list is working. The problem is with free function.
https://i.stack.imgur.com/QpK1j.png
https://i.stack.imgur.com/HXp8d.png
Does anyone have an idea what could be possible wrong with this and how can I fix it?