Passing null to a virtual function call causes a null pointer dereference (GDExtension)

[ZNixian]

I've got a project that overrides ScriptLanguageExtension::_complete_code, one of whose parameters (the third one) is an Object* pointer. Godot passes null to this argument, which causes a fault as Object::get_instance_binding is ultimately called on this pointer:

// Object::get_instance_binding locks a mutex, which is in the zero-page as the object is a null pointer
#0  0x00007ffff7d53b04 in pthread_mutex_lock () from /usr/lib/libc.so.6
#1  0x0000555555a51e2f in __gthread_mutex_lock (__mutex=0x148) at /usr/include/c++/12.2.1/x86_64-pc-linux-gnu/bits/gthr-default.h:749
#2  std::mutex::lock (this=this@entry=0x148) at /usr/include/c++/12.2.1/bits/std_mutex.h:100
// Note this=0x0 - this is called on a null object
#3  0x00005555596d8f29 in Object::get_instance_binding (this=0x0, p_token=0x55555c70c2f0, p_callbacks=0x7ffff49f1690 <godot::Object::___binding_callbacks>) at core/object/object.cpp:1700
// The interface between godot-cpp and the engine, converting the object pointer
#4  0x00005555596ba202 in gdextension_object_get_instance_binding (p_object=<optimized out>, p_token=<optimized out>, p_callbacks=<optimized out>) at core/extension/gdextension_interface.cpp:928
#5  0x00007ffff4904b2b in godot::PtrToArg<godot::Object*>::convert (p_ptr=0x7ffffffface0) at /home/znix/static/programming/c++/gdwren/godot-cpp/include/godot_cpp/core/method_ptrcall.hpp:171
// The result of BIND_VIRTUAL_METHOD and it's associated calls
#6  godot::call_with_ptr_args_retc_helper<WrenLanguage, godot::Dictionary, godot::String const&, godot::String const&, godot::Object*, 0ul, 1ul, 2ul> (p_instance=0x55555fd52380, p_method=&virtual table offset 224, 
    p_args=0x7fffffffad40, r_ret=0x7ffffffface8) at /home/znix/static/programming/c++/gdwren/godot-cpp/include/godot_cpp/core/binder_common.hpp:209
#7  0x00007ffff4901112 in godot::call_with_ptr_args<WrenLanguage, godot::Dictionary, godot::String const&, godot::String const&, godot::Object*> (p_instance=0x55555fd52380, p_method=&virtual table offset 224, p_args=0x7fffffffad40, 
    r_ret=0x7ffffffface8) at /home/znix/static/programming/c++/gdwren/godot-cpp/include/godot_cpp/core/binder_common.hpp:229
#8  0x00007ffff48fb64d in godot::ScriptLanguageExtension::register_virtuals<WrenLanguage, godot::ScriptLanguageExtension>()::{lambda(void*, void const* const*, void*)#24}::operator()(void*, void const* const*, void*) const (
    __closure=0x0, p_instance=0x55555fd52380, p_args=0x7fffffffad40, p_ret=0x7ffffffface8) at /home/znix/static/programming/c++/gdwren/cmake-build-debug/godot-cpp/gen/include/godot_cpp/classes/script_language_extension.hpp:231
#9  0x00007ffff48fb680 in godot::ScriptLanguageExtension::register_virtuals<WrenLanguage, godot::ScriptLanguageExtension>()::{lambda(void*, void const* const*, void*)#24}::_FUN(void*, void const* const*, void*) ()
    at /home/znix/static/programming/c++/gdwren/cmake-build-debug/godot-cpp/gen/include/godot_cpp/classes/script_language_extension.hpp:231
// The in-engine caller
#10 0x00005555591ffc2e in ScriptLanguageExtension::_gdvirtual__complete_code_call<true> (r_ret=..., arg3=0x0, arg2=..., arg1=..., this=0x55555fd523c0) at ./core/object/script_language_extension.h:351
#11 ScriptLanguageExtension::complete_code (this=this@entry=0x55555fd523c0, p_code=..., p_path=..., p_owner=p_owner@entry=0x0, r_options=r_options@entry=0x7fffffffaea0, r_force=@0x7fffffffae9f: false, r_call_hint=...)
    at ./core/object/script_language_extension.h:355

The following diff did fix it, but it feels fairly hacky - I'm not sure if this is the right place for checking for null-ness, or if null is even supposed to be a valid value:

diff --git a/include/godot_cpp/core/method_ptrcall.hpp b/include/godot_cpp/core/method_ptrcall.hpp
index 6b092bb..e917925 100644
--- a/include/godot_cpp/core/method_ptrcall.hpp
+++ b/include/godot_cpp/core/method_ptrcall.hpp
@@ -168,7 +168,10 @@ MAKE_PTRARG_BY_REFERENCE(Variant);
 template <class T>
 struct PtrToArg<T *> {
        _FORCE_INLINE_ static T *convert(const void *p_ptr) {
-               return reinterpret_cast<T *>(godot::internal::gde_interface->object_get_instance_binding(*reinterpret_cast<GDExtensionObjectPtr *>(const_cast<void *>(p_ptr)), godot::internal::token, &T::___binding_callbacks));
+               GDExtensionObjectPtr objPtr = *reinterpret_cast<GDExtensionObjectPtr *>(const_cast<void *>(p_ptr));
+               if (objPtr == nullptr)
+                       return nullptr;
+               return reinterpret_cast<T *>(godot::internal::gde_interface->object_get_instance_binding(objPtr, godot::internal::token, &T::___binding_callbacks));
        }
        typedef Object *EncodeT;
        _FORCE_INLINE_ static void encode(T *p_var, void *p_ptr) {
@@ -179,7 +182,10 @@ struct PtrToArg<T *> {
 template <class T>
 struct PtrToArg<const T *> {
        _FORCE_INLINE_ static const T *convert(const void *p_ptr) {
-               return reinterpret_cast<const T *>(godot::internal::gde_interface->object_get_instance_binding(*reinterpret_cast<GDExtensionObjectPtr *>(const_cast<void *>(p_ptr)), godot::internal::token, &T::___binding_callbacks));
+               GDExtensionObjectPtr objPtr = *reinterpret_cast<GDExtensionObjectPtr *>(const_cast<void *>(p_ptr));
+               if (objPtr == nullptr)
+                       return nullptr;
+               return reinterpret_cast<const T *>(godot::internal::gde_interface->object_get_instance_binding(objPtr, godot::internal::token, &T::___binding_callbacks));
        }
        typedef const Object *EncodeT;
        _FORCE_INLINE_ static void encode(T *p_var, void *p_ptr) {