### Godot version

4.1.beta3

### System information

Fedora Workstation 38 - Godot 4.1.beta3 - Vulkan (Forward+)

### Issue description

**This is an issue created by the production team, we're working on it**

Currently, it's impossible to call virtual functions within GDScript.

This currently returns an error:
```gdscript
# a.gd
extends Node

func _process(delta: float) -> void:
	pass
```

```gdscript
# main.gd
extends Node

var my_node: Node = preload("res://a.gd").new()

func _process(delta: float) -> void:
	my_node._process(delta)  # Cannot call virtual function "_process()" because it hasn't been defined.
```

### Steps to reproduce

1. Create a script (`a.gd`) based on `Node` that declares `_process()`;
2. Create a main node;
3. Attach a script to the main node;
4. Initialize a variable with a new `a.gd` instance;
5. Try to run `_process()` on that node;
6. Find out that it returns an error.

### Minimal reproduction project

[virtual_functions.zip (updated)](https://github.com/godotengine/godot/files/11823992/virtual_functions.zip)


}
	}
}
void GDScriptAnalyzer::reduce_unary_op(GDScriptParser::UnaryOpNode *p_unary_op) {
	reduce_expression(p_unary_op->operand);
	GDScriptParser::DataType result;
	if (p_unary_op->operand == nullptr) {
		result.kind = GDScriptParser::DataType::VARIANT;
		p_unary_op->set_datatype(result);
		return;
	}
	GDScriptParser::DataType operand_type = p_unary_op->operand->get_datatype();
	if (p_unary_op->operand->is_constant) {
		p_unary_op->is_constant = true;
		p_unary_op->reduced_value = Variant::evaluate(p_unary_op->variant_op, p_unary_op->operand->reduced_value, Variant());
		result = type_from_variant(p_unary_op->reduced_value, p_unary_op);
	}
	if (operand_type.is_variant()) {
		result.kind = GDScriptParser::DataType::VARIANT;
		mark_node_unsafe(p_unary_op);
	} else {
		bool valid = false;
		result = get_operation_type(p_unary_op->variant_op, operand_type, valid, p_unary_op);
		if (!valid) {
			push_error(vformat(R"(Invalid operand of type "%s" for unary operator "%s".)", operand_type.to_string(), Variant::get_operator_name(p_unary_op->variant_op)), p_unary_op);
		}
	}
	p_unary_op->set_datatype(result);
}
Variant GDScriptAnalyzer::make_expression_reduced_value(GDScriptParser::ExpressionNode *p_expression, bool &is_reduced) {