### Godot version

Beta 17, master

### System information

Windows 11

### Issue description

Godot gets a hard crash while attempting to code-complete for member `const` of a class.

### Steps to reproduce

```GDScript
enum E { V1 }

const e := E
```

And then type a `.` after the last `E`, which triggers code hints/auto-completion for subscripts based on `E` and causes a hard crash.

Does not happen for `var e := E.V1`.

### Minimal reproduction project

See above.
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) {