### 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)


}
			}
		}
		for (int index = extends_index; index < p_class->extends.size(); index++) {
			GDScriptParser::IdentifierNode *id = p_class->extends[index];
			if (base.kind != GDScriptParser::DataType::CLASS) {
				push_error(vformat(R"(Cannot get nested types for extension from non-GDScript type "%s".)", base.to_string()), id);
				return ERR_PARSE_ERROR;
			}
			reduce_identifier_from_base(id, &base);
			GDScriptParser::DataType id_type = id->get_datatype();
			if (!id_type.is_set()) {
				push_error(vformat(R"(Could not find nested type "%s".)", id->name), id);
				return ERR_PARSE_ERROR;
			} else if (id_type.kind != GDScriptParser::DataType::SCRIPT && id_type.kind != GDScriptParser::DataType::CLASS) {
				push_error(vformat(R"(Identifier "%s" is not a preloaded script or class.)", id->name), id);
				return ERR_PARSE_ERROR;
			}
			base = id_type;
		}
		result = base;
	}
	if (!result.is_set() || result.has_no_type()) {
		
		push_error(vformat(R"(Could not resolve inheritance for class "%s".)", p_class->identifier == nullptr ? "<main>" : p_class->identifier->name), p_class);
		return ERR_PARSE_ERROR;
	}
	
	const GDScriptParser::ClassNode *base_class = result.class_type;
	while (base_class) {