### 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 (p_await->to_await == nullptr) {
		GDScriptParser::DataType await_type;
		await_type.kind = GDScriptParser::DataType::VARIANT;
		p_await->set_datatype(await_type);
		return;
	}
	GDScriptParser::DataType awaiting_type;
	if (p_await->to_await->type == GDScriptParser::Node::CALL) {
		reduce_call(static_cast<GDScriptParser::CallNode *>(p_await->to_await), true);
		awaiting_type = p_await->to_await->get_datatype();
	} else {
		reduce_expression(p_await->to_await);
	}
	if (p_await->to_await->is_constant) {
		p_await->is_constant = p_await->to_await->is_constant;
		p_await->reduced_value = p_await->to_await->reduced_value;
		awaiting_type = p_await->to_await->get_datatype();
	} else {
		awaiting_type.kind = GDScriptParser::DataType::VARIANT;
		awaiting_type.type_source = GDScriptParser::DataType::UNDETECTED;
	}
	p_await->set_datatype(awaiting_type);
#ifdef DEBUG_ENABLED
	awaiting_type = p_await->to_await->get_datatype();
	if (!(awaiting_type.has_no_type() || awaiting_type.is_coroutine || awaiting_type.builtin_type == Variant::SIGNAL)) {
		parser->push_warning(p_await, GDScriptWarning::REDUNDANT_AWAIT);
	}
#endif
}
void GDScriptAnalyzer::reduce_binary_op(GDScriptParser::BinaryOpNode *p_binary_op) {