### 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.
SubscriptNode *attribute = static_cast<SubscriptNode *>(call->callee);
			if (attribute->is_attribute) {
				if (attribute->attribute) {
					call->function_name = attribute->attribute->name;
				}
				make_completion_context(COMPLETION_ATTRIBUTE_METHOD, call->callee);
			} else {
				
				push_error(R"*(Cannot call on an expression. Use ".call()" if it's a Callable.)*");
			}
		} else {
			push_error(R"*(Cannot call on an expression. Use ".call()" if it's a Callable.)*");
		}
	}
	
	CompletionType ct = COMPLETION_CALL_ARGUMENTS;
	if (call->function_name == SNAME("load")) {
		ct = COMPLETION_RESOURCE_PATH;
	}
	push_completion_call(call);
	int argument_index = 0;
	do {
		make_completion_context(ct, call, argument_index++, true);
		if (check(GDScriptTokenizer::Token::PARENTHESIS_CLOSE)) {
			
			break;
		}
		bool use_identifier_completion = current.cursor_place == GDScriptTokenizer::CURSOR_END || current.cursor_place == GDScriptTokenizer::CURSOR_MIDDLE;
		ExpressionNode *argument = parse_expression(false);
		if (argument == nullptr) {