### 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<FileAccess> f = FileAccess::open(p_path, FileAccess::READ, &err);
	if (err) {
		const char *err_name;
		if (err < 0 || err >= ERR_MAX) {
			err_name = "(invalid error code)";
		} else {
			err_name = error_names[err];
		}
		ERR_FAIL_COND_V_MSG(err, err, "Attempt to open script '" + p_path + "' resulted in error '" + err_name + "'.");
	}
	uint64_t len = f->get_length();
	sourcef.resize(len + 1);
	uint8_t *w = sourcef.ptrw();
	uint64_t r = f->get_buffer(w, len);
	ERR_FAIL_COND_V(r != len, ERR_CANT_OPEN);
	w[len] = 0;
	String s;
	if (s.parse_utf8((const char *)w) != OK) {
		ERR_FAIL_V_MSG(ERR_INVALID_DATA, "Script '" + p_path + "' contains invalid unicode (UTF-8), so it was not loaded. Please ensure that scripts are saved in valid UTF-8 unicode.");
	}
	source = s;
	path = p_path;
#ifdef TOOLS_ENABLED
	source_changed_cache = true;
	set_edited(false);
	set_last_modified_time(FileAccess::get_modified_time(path));
#endif 
	return OK;
}
const HashMap<StringName, GDScriptFunction *> &GDScript::debug_get_member_functions() const {