### Godot version

3b086aa06

### System information

ArchLinux x11

### Issue description

```gdscript
extends Node

@export_group("My Properties")
@export var number = 3
@export var string = ""

@export_group("Prefixed Properties", "prefix_")
@export var prefix_number = 3
@export var prefix_string = ""

@export_group("", "")
@export var ungrouped_number = 3
```

![image](https://user-images.githubusercontent.com/70787919/214983963-528c415b-745b-47fc-9777-36ebe31a3060.png)


### Steps to reproduce

- create script
- @export_group
- go inspector

### Minimal reproduction project

‮
Ref<GDScript> res = GDScriptCache::get_shallow_script(p_preload->resolved_path, err, parser->script_path);
				p_preload->resource = res;
				if (err != OK) {
					push_error(vformat(R"(Could not preload resource script "%s".)", p_preload->resolved_path), p_preload->path);
				}
			} else if (ResourceLoader::get_resource_type(p_preload->resolved_path) == "PackedScene") {
				Error err = OK;
				Ref<PackedScene> res = GDScriptCache::get_packed_scene(p_preload->resolved_path, err, parser->script_path);
				p_preload->resource = res;
				if (err != OK) {
					push_error(vformat(R"(Could not preload resource scene "%s".)", p_preload->resolved_path), p_preload->path);
				}
			} else {
				p_preload->resource = ResourceLoader::load(p_preload->resolved_path);
				if (p_preload->resource.is_null()) {
					push_error(vformat(R"(Could not preload resource file "%s".)", p_preload->resolved_path), p_preload->path);
				}
			}
		}
	}
	p_preload->is_constant = true;
	p_preload->reduced_value = p_preload->resource;
	p_preload->set_datatype(type_from_variant(p_preload->reduced_value, p_preload));
}
void GDScriptAnalyzer::reduce_self(GDScriptParser::SelfNode *p_self) {
	p_self->is_constant = false;
	p_self->set_datatype(type_from_metatype(parser->current_class->get_datatype()));
	mark_lambda_use_self();
}
void GDScriptAnalyzer::reduce_subscript(GDScriptParser::SubscriptNode *p_subscript) {