### 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
}
	}
	const Ref<Script> scr = _get_edited_resource();
	if (scr.is_valid()) {
		
		const Color basetype_color = EDITOR_GET("text_editor/theme/highlighting/base_type_color");
		List<String> core_types;
		scr->get_language()->get_core_type_words(&core_types);
		for (const String &E : core_types) {
			highlighter->add_keyword_color(E, basetype_color);
		}
		
		const Color keyword_color = EDITOR_GET("text_editor/theme/highlighting/keyword_color");
		const Color control_flow_keyword_color = EDITOR_GET("text_editor/theme/highlighting/control_flow_keyword_color");
		List<String> keywords;
		scr->get_language()->get_reserved_words(&keywords);
		for (const String &E : keywords) {
			if (scr->get_language()->is_control_flow_keyword(E)) {
				highlighter->add_keyword_color(E, control_flow_keyword_color);
			} else {
				highlighter->add_keyword_color(E, keyword_color);
			}
		}
		
		const Color member_variable_color = EDITOR_GET("text_editor/theme/highlighting/member_variable_color");
		StringName instance_base = scr->get_instance_base_type();
		if (instance_base != StringName()) {
			List<PropertyInfo> plist;
			ClassDB::get_property_list(instance_base, &plist);
			for (const PropertyInfo &E : plist) {