### 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.
Dictionary dictionary;
	for (int i = 0; i < p_dictionary->elements.size(); i++) {
		const GDScriptParser::DictionaryNode::Pair &element = p_dictionary->elements[i];
		bool is_element_key_reduced = false;
		Variant element_key = make_expression_reduced_value(element.key, is_element_key_reduced);
		if (!is_element_key_reduced) {
			return Variant();
		}
		bool is_element_value_reduced = false;
		Variant element_value = make_expression_reduced_value(element.value, is_element_value_reduced);
		if (!is_element_value_reduced) {
			return Variant();
		}
		dictionary[element_key] = element_value;
	}
	dictionary.make_read_only();
	is_reduced = true;
	return dictionary;
}
Variant GDScriptAnalyzer::make_subscript_reduced_value(GDScriptParser::SubscriptNode *p_subscript, bool &is_reduced) {