### 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.
if (base.enum_values.has(name)) {
				p_identifier->set_datatype(type_from_metatype(base));
				p_identifier->is_constant = true;
				p_identifier->reduced_value = base.enum_values[name];
				return;
			}
			
			return;
		} else {
			push_error(R"(Cannot get property from enum value.)", p_identifier);
			return;
		}
	}
	if (base.kind == GDScriptParser::DataType::BUILTIN) {
		if (base.is_meta_type) {
			bool valid = true;
			Variant result = Variant::get_constant_value(base.builtin_type, name, &valid);
			if (valid) {
				p_identifier->is_constant = true;
				p_identifier->reduced_value = result;
				p_identifier->set_datatype(type_from_variant(result, p_identifier));
			} else if (base.is_hard_type()) {
#ifdef TOOLS_ENABLED
#ifndef DISABLE_DEPRECATED
				String rename_hint = String();
				if (GLOBAL_GET(GDScriptWarning::get_settings_path_from_code(GDScriptWarning::Code::RENAMED_IN_GD4_HINT)).booleanize()) {
					const char *renamed_identifier_name = check_for_renamed_identifier(name, p_identifier->type);
					if (renamed_identifier_name) {
						rename_hint = " " + vformat(R"(Did you mean to use "%s"?)", renamed_identifier_name);
					}