### Godot version

4.0-rc1

### System information

Windows 10

### Issue description

The code: `@export @onready var camera_system : Node3D`

Is throwing: `Line 5:The "@onready" annotation will make the default value to be set after the "@export" takes effect and will override it. (Warning treated as error.)` and is crashing the game.

Unchecking "Treat Warning as Errors" seems to have no effect:

![imagen](https://user-images.githubusercontent.com/248383/217900756-8e214c40-68fb-4fb2-8509-a1e689725930.png)

![imagen](https://user-images.githubusercontent.com/248383/217901253-3b758ebc-48e9-40fe-8d77-16fce7cbae88.png)


### Steps to reproduce

- Write `@export @onready var some_var : Node3D`
- In Project Settings, uncheck `Treat Warning as Errors`
- Try to run the project, a `Parser Error` will be thrown.

### Minimal reproduction project

It's as simple as adding one line of code, so I'm not sure a MRP is needed.
SubscriptNode *subscript = alloc_node<SubscriptNode>();
	reset_extents(subscript, p_previous_operand);
	update_extents(subscript);
	make_completion_context(COMPLETION_SUBSCRIPT, subscript);
	subscript->base = p_previous_operand;
	subscript->index = parse_expression(false);
	if (subscript->index == nullptr) {
		push_error(R"(Expected expression after "[".)");
	}
	pop_multiline();
	consume(GDScriptTokenizer::Token::BRACKET_CLOSE, R"(Expected "]" after subscription index.)");
	complete_extents(subscript);
	return subscript;
}
GDScriptParser::ExpressionNode *GDScriptParser::parse_cast(ExpressionNode *p_previous_operand, bool p_can_assign) {