How to solve Realloc(): invalid next size in c

Question

I've been facing this error for quite some time now, and I'm stuck here. I was creating a function that converts a sentence into an array of words, before processing them further, but the problem is that realloc is not looping more than 3 times. I.e., if i use a string of 3 words, the code runs fine, but if the sentence is more than 3 words, I'm stuck on this error

realloc(): invalid next size
zsh: IOT instruction  ./a.out

Here is my code

#include <stdio.h>
#include <string.h>
#include <stdbool.h>
#include <stdlib.h>

char **process_str(char *str)
{
        char **str_ptr, **str_ptr2, *word_ptr,  word[20], chr;
        int i = 0, count = 0, ind = 0, len;
        bool first = true;

        if (str == NULL) return (NULL);
        str_ptr = (char **)malloc(sizeof(char *));
        if (str_ptr == NULL) return (NULL);
        len = strlen(str) + 1;
        while (i < len)
        {
                chr = str[i];
                if ((chr == ' ' || chr == '\0') && ind > 0)
                {
                        word[ind] = '\0';
                        word_ptr = strdup(word);
                        if (first)
                        {
                                *(str_ptr) = word_ptr;
                                first = false;
                        }
                        else
                        {
                                str_ptr2 = (char **)realloc(str_ptr, count + 1);
                                if (str_ptr2 == NULL) return (NULL);
                                *(str_ptr2 + count) = word_ptr;
                                str_ptr = str_ptr2;
                        }
                        ind = 0;
                        count++;
                        i++;
                        continue;
                }
                if (chr != ' ')
                {
                        word[ind] = chr;
                        ind++;
                }
                i++;
        }
        str_ptr2 = (char **)realloc(str_ptr, count + 1);
         if (str_ptr2 == NULL) return (NULL);
       *(str_ptr2 + count) = NULL;
       str_ptr = str_ptr2;
        return (str_ptr);
}

and i tested it using this function

int main(void)
{
        int i = 1;
        char **ptr, *s_ptr;
        char *str = "please please anf dsd  it for";

        ptr = process_str(str);
        printf("done step one\n");
        if (ptr == NULL)
        {
                printf("ptr is NULL");
                return (1);
        }
        s_ptr = ptr[0];
        while (s_ptr != NULL)
        {
                printf("String: %s\n", s_ptr);
                s_ptr = ptr[i];
                i++;
        }
        return (0);
}

if i change the value of str in main, to something like str = "This is home" the code executes fine. Please any help is appreciated.