### 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.
Ref<GDScript> sqscr = p_resource;
	ERR_FAIL_COND_V(sqscr.is_null(), ERR_INVALID_PARAMETER);
	String source = sqscr->get_source_code();
	{
		Error err;
		Ref<FileAccess> file = FileAccess::open(p_path, FileAccess::WRITE, &err);
		ERR_FAIL_COND_V_MSG(err, err, "Cannot save GDScript file '" + p_path + "'.");
		file->store_string(source);
		if (file->get_error() != OK && file->get_error() != ERR_FILE_EOF) {
			return ERR_CANT_CREATE;
		}
	}
	if (ScriptServer::is_reload_scripts_on_save_enabled()) {
		GDScriptLanguage::get_singleton()->reload_tool_script(p_resource, true);
	}
	return OK;
}
void ResourceFormatSaverGDScript::get_recognized_extensions(const Ref<Resource> &p_resource, List<String> *p_extensions) const {
	if (Object::cast_to<GDScript>(*p_resource)) {
		p_extensions->push_back("gd");
	}
}
bool ResourceFormatSaverGDScript::recognize(const Ref<Resource> &p_resource) const {
	return Object::cast_to<GDScript>(*p_resource) != nullptr;
}