toml::find<std::string> with idx will cause segfault

[CNOCTAVE]

Example toml string:
[a]\n name = "A"\n [a.b]\n name = "B"\n [a.b.c]\n name = "C"\n [a.b.c.d]\n name = "D"

std::string result = toml::find<std::string>(data, (const std::size_t) 2);
will cause segfault.