why is there an error?
int make_friends(const char *name1, const char *name2, User *head) {
    int error;
    if (strcmp(name1, name2) == 0){
        error = 3;
    }
    if (head == NULL){
        return 4;
    }
    else{
        if (head->next == NULL){
            if (strcmp(head->name, name1) != 0){
                return 4;
            }
        }
        User *first_user = find_user(name1, head);
        User *second_user = find_user(name2, head);

        if (first_user == NULL || second_user == NULL){
            return 4;
        }

        int stop = 0;

        if ((first_user->friends[9] != NULL) && (second_user->friends[9] != NULL)){
             for (int i = 0; i < 10; i++){
                if(first_user->friends[i] == second_user){
                    if (error < 1){
                        error = 1;
                    } 
                }
                    if (stop == 0){
                        if (first_user->friends[i] == NULL){
                            first_user->friends[i] = second_user;
                            stop = 1;
                            error = 0;
                    }
                }
                 fprintf(stdout, "%s\n", first_user->friends[i]->name);
                
        }
        }
        if (first_user->friends[9] != NULL && second_user->friends[9] != NULL){
        for (int j = 0; j < 10; j++){
            if(second_user->friends[j] == first_user){
                if (error < 1){
                    error = 1;
                    }
                   }
                if (stop == 0){
                    if (second_user->friends[j] == NULL){
                        second_user->friends[j] = first_user;
                        stop = 1;
                        error = 0;
                    }
                }
                fprintf(stdout, "%s\n", first_user->friends[j]->name);

            }
        }
    
    }
    if (error ==0){
        return 0;
    }
    else{
        return error;
    }
}
