A fatal error about the handle is invalid about plthook HOT 6 CLOSED

#include <stdio.h>
#include <string.h>
#include <link.h>
#include <dlfcn.h>

void test() {
  struct link_map *lmap = _r_debug.r_map; // See link.h
  while (lmap != NULL) {
    if (strstr(lmap->l_name, "libtest.so") != NULL) {
      printf("%p: link_map address of libtest.so searched from the global variable _r_debug\n", lmap);
    } else if (strstr(lmap->l_name, "libc.so.6") != NULL) {
      printf("%p: link_map address of libc.so.6 searched from the global variable _r_debug\n", lmap);
    }
    lmap = lmap->l_next;
  }
}

int main()
{
  printf("-------------------\n");
  test();
  printf("-------------------\n");

  void* handle = dlopen("libtest.so", RTLD_LAZY);
  if (handle != NULL) {
    printf("%p: dlopen handle of libtest.so\n", handle);
  }

  printf("-------------------\n");
  test();
  dlclose(handle);

  printf("-------------------\n");
  test();
  printf("-------------------\n");
  return 0;
}

gcc -o test test.c -ldl

ldd test
  linux-vdso.so.1 (0x00007ffe6d3fa000)
  libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x00007f72cc1fa000)
  libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f72cbe09000)
  /lib64/ld-linux-x86-64.so.2 (0x00007f72cc600000)

./test
-------------------
0x7f18128ec4f0: link_map address of libc.so.6 searched from the global variable _r_debug
-------------------
0x55b015f49690: dlopen handle of libtest.so
-------------------
0x7f18128ec4f0: link_map address of libc.so.6 searched from the global variable _r_debug
0x55b015f49690: link_map address of libtest.so searched from the global variable _r_debug
-------------------
0x7f18128ec4f0: link_map address of libc.so.6 searched from the global variable _r_debug
-------------------

#include <stdio.h>
#include <string.h>
#include <link.h>
#include <dlfcn.h>

#include <plthook.h>

static double strtod_cdecl_hook_func(const char *str, char **endptr)
{
    printf("strtod_cdecl_hook_func\n");

    return 0;
}

int main()
{
  plthook_t* plthook = NULL;
  const char* filename = "libtest.so";
  plthook_open(&plthook, filename);

  unsigned int pos = 0;
  const char* name = NULL;
  void **addr = NULL;
  const char* funcname = "strtod_cdecl";
  unsigned int found = 0;
  while (plthook_enum(plthook, &pos, &name, &addr) == 0) {
    if (strcmp(funcname, name) == 0) {
        found = 1;
        break;
    }
  }
  if (0 != found)
  {
    plthook_replace(plthook, funcname, (void*)strtod_cdecl_hook_func, NULL);
  }

  plthook_close(plthook);

  // strtod_cdecl("3.7", NULL);

  return 0;
}

gcc -o test test.c ../plthook_elf.c -ldl