c++ - Why does this error appear during compilation?(CodeWars)

Question

Here below is the error that ocuurs after the compilation. I've been solving 5kyu task on CodeWars.I passed all test cases, but when I want to attempt, these errors pop up:

double free or corruption (out)
UndefinedBehaviorSanitizer:DEADLYSIGNAL
==1==ERROR: UndefinedBehaviorSanitizer: SEGV on unknown address 0x000000000000 (pc 0x7f64918f2a10 bp 0x7fff85a912b0 sp 0x7fff85a91060 T1)
==1==The signal is caused by a READ memory access.
==1==Hint: address points to the zero page.
==1==WARNING: invalid path to external symbolizer!
==1==WARNING: Failed to use and restart external symbolizer!
    #0 0x7f64918f2a0f  (/lib/x86_64-linux-gnu/libc.so.6+0x40a0f)
    #1 0x7f649193b966  (/lib/x86_64-linux-gnu/libc.so.6+0x89966)
    #2 0x7f64919429d9  (/lib/x86_64-linux-gnu/libc.so.6+0x909d9)
    #3 0x7f6491949f69  (/lib/x86_64-linux-gnu/libc.so.6+0x97f69)
    #4 0x429a0a  (/workspace/test+0x429a0a)
    #5 0x426f0e  (/workspace/test+0x426f0e)
    #6 0x426a17  (/workspace/test+0x426a17)
    #7 0x42661b  (/workspace/test+0x42661b)
    #8 0x42d8e5  (/workspace/test+0x42d8e5)
    #9 0x425ccd  (/workspace/test+0x425ccd)
    #10 0x7f64918d3bf6  (/lib/x86_64-linux-gnu/libc.so.6+0x21bf6)
    #11 0x404619  (/workspace/test+0x404619)

UndefinedBehaviorSanitizer can not provide additional info.
==1==ABORTING

MY CODE IS:

#include <iostream>
#include <cstring>


using namespace std;


string interpreter(const string &code,const string &tape){
    string str_1 = ">";
    string str_2 = "<";
    string str_3 = "*";
    string str_4 = "[";
    string str_5 = "]";
    string str_6 = "0";
    string str_7 = "1";
    string copy_code;copy_code=code;
    string result;result=tape;
    int step = 0;
    for(unsigned long i=0;i<copy_code.size();++i){
        if(str_1==string(1,copy_code[i]))step++;
        if(str_2==string(1,copy_code[i]))step--;
        if(str_3==string(1,copy_code[i])){
            //flip(result[step])step=0;}
            if(result[step] == str_6[0]){
                result[step] = str_7[0];
            }else {
                result[step] = str_6[0];
            }
        }
    }
  return result;
}

question from:https://stackoverflow.com/questions/65927067/why-does-this-error-appear-during-compilationcodewars

Answer 1

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