Error while finding the running sum of an array in C++ using vectors

Why am i getting this error, while finding the running sum of an array in c++?

Line 1034: Char 34: runtime error: addition of unsigned offset to 0x6020000000b0 overflowed to 0x6020000000ac (stl_vector.h)
SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior /usr/bin/../lib/gcc/x86_64-linux-gnu/9/../../../../include/c++/9/bits/stl_vector.h:1043:34".

the code is:

    class Solution {
    public:
        vector<int> runningSum(vector<int>& nums) {
          vector<int> temp(nums.size());
            nums[0]=temp[0];
            for(int i=0;i<nums.size();i++){
                temp[i]=temp[i-1]+nums[i];
            }
              return temp;
        }
    };

>Solution :

nums[0]=temp[0] is incorrect, since temp[0] is 0 currently. It should be the other way around.

Also, the lower bound for the for loop should be i=1.

class Solution {
public:
    vector<int> runningSum(vector<int>& nums) {
      vector<int> temp(nums.size());
        temp[0] = nums[0];
        for(int i=1;i<nums.size();i++){
            temp[i]=temp[i-1]+nums[i];
        }
          return temp;
    }
};