Line 86: Char 2: runtime error: store to null pointer of type 'std::_Bit_type' (aka 'unsigned long') (stl_bvector.h)

I'm trying Sieve of Eratosthenes and trying a problem in leetcode but I'm getting this error.

Line 86: Char 2: runtime error: store to null pointer of type 'std::_Bit_type' (aka 'unsigned long') (stl_bvector.h)
SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior /usr/bin/../lib/gcc/x86_64-linux-gnu/9/../../../../include/c++/9/bits/stl_bvector.h:95:2..

below is my code :

class Solution {
public:
    int countPrimes(int n)
    {
        int count = 0;

        vector<bool> prime(n, true);

        prime[0] = prime[1] = false;

        for (int i = 2; i < n; i++) {
            if (prime[i]) {
                count++;
                for (int j = i * 2; j < n; j = j + i) {
                    prime[j] = 0;
                }
            }
        }
        return count;
    }
};

I have tried finding solutions online but still unable to rectify it.

I know that error roughly means a index is getting out of bounds but I cant understand how? please explain that.

You don't check n value before accessing prime[0] and prime[1], n can be 0 or 1.

runtime error: store to null pointer is a clear sign that n is 0 (the vector does not have data, it's nullptr and vector's size is 0).