Avoid recreating internals during type deallocation at shutdown.

Author: b-pass

include/pybind11/detail/class.h

@@ -207,7 +207,7 @@ extern "C" inline PyObject *pybind11_meta_call(PyObject *type, PyObject *args, P
 
 /// Cleanup the type-info for a pybind11-registered type.
 extern "C" inline void pybind11_meta_dealloc(PyObject *obj) {
-    with_internals([obj](internals &internals) {
+    with_internals_if_internals([obj](internals &internals) {
         auto *type = (PyTypeObject *) obj;
 
         // A pybind11-registered type will:

include/pybind11/detail/internals.h

@@ -322,8 +322,9 @@ struct internals {
         // completely shut down, In that case, we should not decref these objects because pymalloc
         // is gone.
         if (is_interpreter_alive()) {
-            Py_CLEAR(static_property_type);
+            Py_CLEAR(instance_base);
             Py_CLEAR(default_metaclass);
+            Py_CLEAR(static_property_type);
         }
     }
 };
@@ -870,6 +871,17 @@ inline auto with_internals(const F &cb) -> decltype(cb(get_internals())) {
     return cb(internals);
 }
 
+template <typename F>
+inline void with_internals_if_internals(const F &cb) {
+    auto &ppmgr = get_internals_pp_manager();
+    auto &internals_ptr = *ppmgr.get_pp();
+    if (internals_ptr) {
+        auto &internals = *internals_ptr;
+        PYBIND11_LOCK_INTERNALS(internals);
+        cb(internals);
+    }
+}
+
 template <typename F>
 inline auto with_exception_translators(const F &cb)
     -> decltype(cb(get_internals().registered_exception_translators,