onig_region_clear(OnigRegion* region)
{
  int i;

  for (i = 0; i < region->num_regs; i++) {
    region->beg[i] = region->end[i] = ONIG_REGION_NOTPOS;
  }
#ifdef USE_CAPTURE_HISTORY
  history_root_free(region);
#endif
}

The product dereferences a pointer that it expects to be valid but is NULL.