### 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 *attribute = alloc_node<SubscriptNode>();
	reset_extents(attribute, p_previous_operand);
	update_extents(attribute);
	if (for_completion) {
		bool is_builtin = false;
		if (p_previous_operand && p_previous_operand->type == Node::IDENTIFIER) {
			const IdentifierNode *id = static_cast<const IdentifierNode *>(p_previous_operand);
			Variant::Type builtin_type = get_builtin_type(id->name);
			if (builtin_type < Variant::VARIANT_MAX) {
				make_completion_context(COMPLETION_BUILT_IN_TYPE_CONSTANT_OR_STATIC_METHOD, builtin_type, true);
				is_builtin = true;
			}
		}
		if (!is_builtin) {
			make_completion_context(COMPLETION_ATTRIBUTE, attribute, -1, true);
		}
	}
	attribute->base = p_previous_operand;
	if (!consume(GDScriptTokenizer::Token::IDENTIFIER, R"(Expected identifier after "." for attribute access.)")) {
		complete_extents(attribute);
		return attribute;
	}
	attribute->is_attribute = true;
	attribute->attribute = parse_identifier();
	complete_extents(attribute);
	return attribute;
}
GDScriptParser::ExpressionNode *GDScriptParser::parse_subscript(ExpressionNode *p_previous_operand, bool p_can_assign) {