### 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> cached_script = GDScriptCache::get_cached_script(source_path);
		if (!source_path.is_empty() && cached_script.is_null()) {
			MutexLock lock(GDScriptCache::singleton->mutex);
			GDScriptCache::singleton->shallow_gdscript_cache[source_path] = Ref<GDScript>(this);
		}
	}
	valid = false;
	GDScriptParser parser;
	Error err = parser.parse(source, path, false);
	if (err) {
		if (EngineDebugger::is_active()) {
			GDScriptLanguage::get_singleton()->debug_break_parse(_get_debug_path(), parser.get_errors().front()->get().line, "Parser Error: " + parser.get_errors().front()->get().message);
		}
		
		_err_print_error("GDScript::reload", path.is_empty() ? "built-in" : (const char *)path.utf8().get_data(), parser.get_errors().front()->get().line, ("Parse Error: " + parser.get_errors().front()->get().message).utf8().get_data(), false, ERR_HANDLER_SCRIPT);
		reloading = false;
		return ERR_PARSE_ERROR;
	}
	GDScriptAnalyzer analyzer(&parser);
	err = analyzer.analyze();
	if (err) {
		if (EngineDebugger::is_active()) {
			GDScriptLanguage::get_singleton()->debug_break_parse(_get_debug_path(), parser.get_errors().front()->get().line, "Parser Error: " + parser.get_errors().front()->get().message);
		}
		const List<GDScriptParser::ParserError>::Element *e = parser.get_errors().front();
		while (e != nullptr) {
			_err_print_error("GDScript::reload", path.is_empty() ? "built-in" : (const char *)path.utf8().get_data(), e->get().line, ("Parse Error: " + e->get().message).utf8().get_data(), false, ERR_HANDLER_SCRIPT);
			e = e->next();
		}
		reloading = false;