…` triggered by stl.h `array_caster`:

```
clang++ -o pybind11/tests/test_stl_no_default_ctor.os -c -std=c++17 -fPIC -fvisibility=hidden -O0 -g -Wall -Wextra -Wconversion -Wcast-qual -Wdeprecated -Wundef -Wnon-virtual-dtor -Wunused-result -Werror -isystem /usr/include/python3.10 -isystem /usr/include/eigen3 -DPYBIND11_STRICT_ASSERTS_CLASS_HOLDER_VS_TYPE_CASTER_MIX -DPYBIND11_ENABLE_TYPE_CASTER_ODR_GUARD_IF_AVAILABLE -DPYBIND11_TEST_BOOST -Ipybind11/include -I/usr/local/google/home/rwgk/forked/pybind11/include -I/usr/local/google/home/rwgk/clone/pybind11/include /usr/local/google/home/rwgk/forked/pybind11/tests/test_stl_no_default_ctor.cpp
In file included from /usr/local/google/home/rwgk/forked/pybind11/tests/test_stl_no_default_ctor.cpp:1:
In file included from /usr/local/google/home/rwgk/forked/pybind11/include/pybind11/stl.h:12:
In file included from /usr/local/google/home/rwgk/forked/pybind11/include/pybind11/pybind11.h:13:
In file included from /usr/local/google/home/rwgk/forked/pybind11/include/pybind11/detail/class.h:12:
In file included from /usr/local/google/home/rwgk/forked/pybind11/include/pybind11/attr.h:14:
In file included from /usr/local/google/home/rwgk/forked/pybind11/include/pybind11/cast.h:18:
/usr/local/google/home/rwgk/forked/pybind11/include/pybind11/detail/type_caster_odr_guard.h:111:5: error: call to implicitly-deleted default constructor of 'pybind11::detail::type_caster<std::array<pybind11_tests::stl_no_default_ctor::Node, 2>>'
    type_caster_odr_guard() {
    ^
/usr/bin/../lib/gcc/x86_64-linux-gnu/12/../../../../include/c++/12/tuple:190:9: note: in instantiation of member function 'pybind11::detail::type_caster_odr_guard<std::array<pybind11_tests::stl_no_default_ctor::Node, 2>, pybind11::detail::type_caster<std::array<pybind11_tests::stl_no_default_ctor::Node, 2>>>::type_caster_odr_guard' requested here
      : _M_head_impl() { }
        ^
/usr/local/google/home/rwgk/forked/pybind11/include/pybind11/pybind11.h:104:9: note: in instantiation of function template specialization 'pybind11::cpp_function::initialize<(lambda at /usr/local/google/home/rwgk/forked/pybind11/include/pybind11/pybind11.h:1583:29), void, pybind11_tests::stl_no_default_ctor::NodeArray &, const std::array<pybind11_tests::stl_no_default_ctor::Node, 2> &, pybind11::is_method>' requested here
        initialize(
        ^
/usr/local/google/home/rwgk/forked/pybind11/include/pybind11/pybind11.h:1583:16: note: in instantiation of function template specialization 'pybind11::cpp_function::cpp_function<(lambda at /usr/local/google/home/rwgk/forked/pybind11/include/pybind11/pybind11.h:1583:29), pybind11::is_method, void>' requested here
        return cpp_function([pm](T &c, const D &value) { c.*pm = value; }, is_method(hdl));
               ^
/usr/local/google/home/rwgk/forked/pybind11/include/pybind11/pybind11.h:1926:54: note: in instantiation of function template specialization 'pybind11::property_cpp_function<pybind11_tests::stl_no_default_ctor::NodeArray, std::array<pybind11_tests::stl_no_default_ctor::Node, 2>>::write<std::array<pybind11_tests::stl_no_default_ctor::Node, 2> pybind11_tests::stl_no_default_ctor::NodeArray::*, 0>' requested here
                     property_cpp_function<type, D>::write(pm, *this),
                                                     ^
/usr/local/google/home/rwgk/forked/pybind11/tests/test_stl_no_default_ctor.cpp:32:10: note: in instantiation of function template specialization 'pybind11::class_<pybind11_tests::stl_no_default_ctor::NodeArray>::def_readwrite<pybind11_tests::stl_no_default_ctor::NodeArray, std::array<pybind11_tests::stl_no_default_ctor::Node, 2>>' requested here
        .def_readwrite("arr", &NodeArray::arr);
         ^
/usr/local/google/home/rwgk/forked/pybind11/include/pybind11/stl.h:288:7: note: default constructor of 'type_caster<std::array<pybind11_tests::stl_no_default_ctor::Node, 2>>' is implicitly deleted because base class 'array_caster<std::array<Node, 2UL>, pybind11_tests::stl_no_default_ctor::Node, false, 2UL>' has a deleted default constructor
    : array_caster<std::array<Type, Size>, Type, false, Size> {};
      ^
/usr/local/google/home/rwgk/forked/pybind11/include/pybind11/stl.h:278:5: note: default constructor of 'array_caster<std::array<pybind11_tests::stl_no_default_ctor::Node, 2>, pybind11_tests::stl_no_default_ctor::Node, false, 2>' is implicitly deleted because field 'value' has a deleted default constructor
    PYBIND11_TYPE_CASTER_RVPP(ArrayType,
    ^
/usr/local/google/home/rwgk/forked/pybind11/include/pybind11/cast.h:262:5: note: expanded from macro 'PYBIND11_TYPE_CASTER_RVPP'
    PYBIND11_TYPE_CASTER_IMPL(type, py_name, ::pybind11::return_value_policy_pack)
    ^
/usr/local/google/home/rwgk/forked/pybind11/include/pybind11/cast.h:232:10: note: expanded from macro 'PYBIND11_TYPE_CASTER_IMPL'
    type value;                                                                                   \
         ^
/usr/bin/../lib/gcc/x86_64-linux-gnu/12/../../../../include/c++/12/array:115:56: note: default constructor of 'array<pybind11_tests::stl_no_default_ctor::Node, 2>' is implicitly deleted because field '_M_elems' has no default constructor
      typename _AT_Type::_Type                         _M_elems;
                                                       ^
1 error generated.
```

…a default constructor.

…8.5 compilation errors.