made it backwards compatible from 4.2.X down to 4.1.2

src/editor_presence.cpp

@@ -2,6 +2,7 @@
 #include "lib/discord_game_sdk/cpp/discord.h"
 #include <godot_cpp/core/class_db.hpp>
 #include <godot_cpp/variant/utility_functions.hpp>
+#include <godot_cpp/classes/scene_tree.hpp>
 
 EditorPresence *EditorPresence::singleton = nullptr;
 
@@ -44,7 +45,7 @@ void EditorPresence::_process(double delta)
 {
     if (state_string.utf8() != activity.GetState())
     {
-        godot::Node *edited_scene_root = editor_interface->get_edited_scene_root();
+        godot::Node *edited_scene_root = get_tree()->get_edited_scene_root();
         activity.SetState(String("Editing: \"" + edited_scene_root->get_scene_file_path() + "\"").replace("res://", "").utf8());
         if (result == discord::Result::Ok)
             core->ActivityManager().UpdateActivity(activity, [](discord::Result result) {});

src/editor_presence.h

@@ -8,6 +8,7 @@
 #include <godot_cpp/classes/project_settings.hpp>
 #include <godot_cpp/classes/engine.hpp>
 #include <godot_cpp/classes/time.hpp>
+#include <godot_cpp/classes/tree.hpp>
 
 using namespace godot;