### 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.
#include "gdscript_parser.h"
#include "core/config/project_settings.h"
#include "core/io/file_access.h"
#include "core/io/resource_loader.h"
#include "core/math/math_defs.h"
#include "gdscript.h"
#include "scene/main/multiplayer_api.h"
#ifdef DEBUG_ENABLED
#include "core/os/os.h"
#include "core/string/string_builder.h"
#include "gdscript_warning.h"
#include "servers/text_server.h"
#endif 
#ifdef TOOLS_ENABLED
#include "editor/editor_settings.h"
#endif 
static HashMap<StringName, Variant::Type> builtin_types;
Variant::Type GDScriptParser::get_builtin_type(const StringName &p_type) {