为什么我不能返回向量<向量<int>>(进程返回 -1073741819 (0xC0000005))

我试图用C++制作一个基于网格的程序。但是每次运行它时，我都会收到相同的错误(在标题中显示(。我知道这是一个很常见的错误，但在仔细阅读代码后，我无法发现任何错误：

#include <iostream>
#include <vector>
using namespace std;
using grid = vector<vector<int>>;
int getNeighboursCount(grid g,int x,int y)
{
int nCount = 0;
if(x > 0 && y > 0){if(g[x-1][y-1] == 1){++nCount;};};
if(x > 0){if(g[x-1][y] == 1){++nCount;};};
if(y > 0){if(g[x][y-1] == 1){++nCount;};};
if(x < g.size() && y < g[x].size()){if(g[x+1][y+1] == 1){++nCount;};};
if(x < g.size()){if(g[x+1][y] == 1){++nCount;};};
if(y > g[x].size()){if(g[x][y+1] == 1){++nCount;};};
if(x > 0 && y < g[x].size()){if(g[x-1][y+1 == 1]){++nCount;};};
if(x < g.size() && y > 0){if(g[x+1][y-1] == 1){++nCount;};};
return nCount;
}
grid testCell(grid g, grid gN, int x, int y)
{
gN = g;
auto nCount = getNeighboursCount(g, x, y);
if(g[x][y] == 1) //1 == TRUE == alive
{
if(nCount == 3 || nCount == 2){gN[x][y] == 1;} //Keep status
else
{
gN[x][y] = 0;
}
}
else if(g[x][y] == 0)
{
if(nCount == 3){gN[x][y] = 1;}
else {gN[x][y] == 0;};
}
return gN;
}
grid step(grid g, grid gN)
{
for(int i = 0; i < g.size(); ++i)
{
for(int j = 0; j < g[i].size(); ++j)
{
gN = testCell(g, gN, i, j);
}
}
// works fine till here...
return gN;
}
int main()
{
grid g =
{ ...
// 40 times 40 grid of 0
};
output(g);
string useless;
grid gN = g;
while(getline(cin, useless))
{
gN = step(g, gN);
output(gN);
}
}

因此，当我启动程序时，它会按预期打印出整个网格。但是当它到达gN = step(...);我得到一个错误的地步时。但是我能够发现它与 swap(( 函数的return gN;语句有关。

感谢帮助