### 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.
base_type = make_builtin_meta_type(GDScriptParser::get_builtin_type(base_id->name));
		} else {
			reduce_expression(subscript->base);
			base_type = subscript->base->get_datatype();
			is_self = subscript->base->type == GDScriptParser::Node::SELF;
		}
	} else {
		
		
		p_call->set_datatype(call_type);
		mark_node_unsafe(p_call);
		return;
	}
	bool is_static = false;
	bool is_vararg = false;
	int default_arg_count = 0;
	GDScriptParser::DataType return_type;
	List<GDScriptParser::DataType> par_types;
	bool is_constructor = (base_type.is_meta_type || (p_call->callee && p_call->callee->type == GDScriptParser::Node::IDENTIFIER)) && p_call->function_name == SNAME("new");
	if (get_function_signature(p_call, is_constructor, base_type, p_call->function_name, return_type, par_types, default_arg_count, is_static, is_vararg)) {
		
		for (const KeyValue<int, GDScriptParser::ArrayNode *> &E : arrays) {
			int index = E.key;
			if (index < par_types.size() && par_types[index].has_container_element_type()) {
				update_array_literal_element_type(E.value, par_types[index].get_container_element_type());
			}
		}
		validate_call_arg(par_types, default_arg_count, is_vararg, p_call);
		if (base_type.kind == GDScriptParser::DataType::ENUM && base_type.is_meta_type) {