### 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.
owner = _baseptr->native->instantiate();
	} else {
		owner = memnew(RefCounted); 
	}
	ERR_FAIL_COND_V_MSG(!owner, Variant(), "Can't inherit from a virtual class.");
	RefCounted *r = Object::cast_to<RefCounted>(owner);
	if (r) {
		ref = Ref<RefCounted>(r);
	}
	GDScriptInstance *instance = _create_instance(p_args, p_argcount, owner, r != nullptr, r_error);
	if (!instance) {
		if (ref.is_null()) {
			memdelete(owner); 
		}
		return Variant();
	}
	if (ref.is_valid()) {
		return ref;
	} else {
		return owner;
	}
}
bool GDScript::can_instantiate() const {
#ifdef TOOLS_ENABLED
	return valid && (tool || ScriptServer::is_scripting_enabled());
#else
	return valid;
#endif
}
Ref<Script> GDScript::get_base_script() const {