end_sentinel doesn't have a the_range_ member

[rimmartin]

Hi, at https://github.com/stdgraph/graph-v2/blob/master/include/graph/views/depth_first_search.hpp#L340 there is an inner struct end_sentinel with an == overload looking unsuccessfully for the_range_ on itself as rhs isend_sentinel type. There is a the_range_ on the inner sibling iterator but I'm not discerning what the intended design is.

Compiling I'm currently hitting

./cpp_modules/graph-v2/include/graph/views/depth_first_search.hpp:340:74: error: ‘const struct graph::vertices_depth_first_search_view<G, void, Alloc>::end_sentinel’ has no member named ‘the_range_’ [-Wtemplate-body]
  340 |     bool operator==(const end_sentinel& rhs) const noexcept { return rhs.the_range_->S_.empty(); }
      |                                                                          ^~~~~~~~~~

[rimmartin]

it happens again at line 570