### 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.
#ifdef TOOLS_ENABLED
	PlaceHolderScriptInstance *si = memnew(PlaceHolderScriptInstance(GDScriptLanguage::get_singleton(), Ref<Script>(this), p_this));
	placeholders.insert(si);
	_update_exports(nullptr, false, si);
	return si;
#else
	return nullptr;
#endif
}
bool GDScript::instance_has(const Object *p_this) const {
	MutexLock lock(GDScriptLanguage::singleton->mutex);
	return instances.has((Object *)p_this);
}
bool GDScript::has_source_code() const {
	return !source.is_empty();
}
String GDScript::get_source_code() const {
	return source;
}
void GDScript::set_source_code(const String &p_code) {
	if (source == p_code) {
		return;
	}
	source = p_code;
#ifdef TOOLS_ENABLED
	source_changed_cache = true;
#endif
}
#ifdef TOOLS_ENABLED
void GDScript::_update_exports_values(HashMap<StringName, Variant> &values, List<PropertyInfo> &propnames) {