### Godot version

3.5.1mono

### System information

windows10

### Issue description

Error message
 scene/main/node.cpp:1362 - Index p_index = 0 is out of bounds (data.children.size() = 0).
 scene/main/node.cpp:397 - Parameter "p_child" is null.
 scene/gui/tab_container.cpp:593 - Index p_current = 0 is out of bounds (get_tab_count() = 0).
See "Steps to reproduce for details"

### Steps to reproduce

Set an external text editor
Create a script
Drop the script to the built-in text editor like this image:
![image](https://user-images.githubusercontent.com/119792950/209504041-039f2620-5e42-4c0f-8c41-cd24486fb3d2.png)
And got error message:
 scene/main/node.cpp:1362 - Index p_index = 0 is out of bounds (data.children.size() = 0).
 scene/main/node.cpp:397 - Parameter "p_child" is null.
 scene/gui/tab_container.cpp:593 - Index p_current = 0 is out of bounds (get_tab_count() = 0).

### Minimal reproduction project

An empty project
current_theme = "";
	script_editor_cache.instantiate();
	script_editor_cache->load(EditorPaths::get_singleton()->get_project_settings_dir().path_join("script_editor_cache.cfg"));
	completion_cache = memnew(EditorScriptCodeCompletionCache);
	restoring_layout = false;
	waiting_update_names = false;
	pending_auto_reload = false;
	auto_reload_running_scripts = true;
	members_overview_enabled = EDITOR_GET("text_editor/script_list/show_members_overview");
	help_overview_enabled = EDITOR_GET("text_editor/help/show_help_index");
	VBoxContainer *main_container = memnew(VBoxContainer);
	add_child(main_container);
	menu_hb = memnew(HBoxContainer);
	main_container->add_child(menu_hb);
	script_split = memnew(HSplitContainer);
	main_container->add_child(script_split);