### 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)


}
		}
	} else if (!p_is_lambda && function_name == GDScriptLanguage::get_singleton()->strings._static_init) {
		
		GDScriptParser::DataType return_type;
		return_type.kind = GDScriptParser::DataType::BUILTIN;
		return_type.builtin_type = Variant::NIL;
		p_function->set_datatype(return_type);
		if (p_function->return_type) {
			GDScriptParser::DataType declared_return = resolve_datatype(p_function->return_type);
			if (declared_return.kind != GDScriptParser::DataType::BUILTIN || declared_return.builtin_type != Variant::NIL) {
				push_error("Static constructor cannot have an explicit return type.", p_function->return_type);
			}
		}
	} else {
		if (p_function->return_type != nullptr) {
			p_function->set_datatype(type_from_metatype(resolve_datatype(p_function->return_type)));
		} else {
			
			
			GDScriptParser::DataType return_type;
			return_type.type_source = GDScriptParser::DataType::INFERRED;
			return_type.kind = GDScriptParser::DataType::VARIANT;
			p_function->set_datatype(return_type);
		}
#ifdef TOOLS_ENABLED
		
		
		GDScriptParser::DataType base_type = parser->current_class->base_type;
		base_type.is_meta_type = false;