### 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.
if (!for_completion) {
		return;
	}
	CompletionCall call;
	call.call = p_call;
	call.argument = 0;
	completion_call_stack.push_back(call);
	if (previous.cursor_place == GDScriptTokenizer::CURSOR_MIDDLE || previous.cursor_place == GDScriptTokenizer::CURSOR_END || current.cursor_place == GDScriptTokenizer::CURSOR_BEGINNING) {
		completion_call = call;
	}
}
void GDScriptParser::pop_completion_call() {
	if (!for_completion) {
		return;
	}
	ERR_FAIL_COND_MSG(completion_call_stack.is_empty(), "Trying to pop empty completion call stack");
	completion_call_stack.pop_back();
}
void GDScriptParser::set_last_completion_call_arg(int p_argument) {
	if (!for_completion || passed_cursor) {
		return;
	}
	ERR_FAIL_COND_MSG(completion_call_stack.is_empty(), "Trying to set argument on empty completion call stack");
	completion_call_stack.back()->get().argument = p_argument;
}
Error GDScriptParser::parse(const String &p_source_code, const String &p_script_path, bool p_for_completion) {