### 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)


GDScriptParser::DataType nil_type;
	nil_type.builtin_type = Variant::NIL;
	nil_type.type_source = GDScriptParser::DataType::ANNOTATED_INFERRED;
	return get_operation_type(p_operation, p_a, nil_type, r_valid, p_source);
}
GDScriptParser::DataType GDScriptAnalyzer::get_operation_type(Variant::Operator p_operation, const GDScriptParser::DataType &p_a, const GDScriptParser::DataType &p_b, bool &r_valid, const GDScriptParser::Node *p_source) {
	if (p_operation == Variant::OP_AND || p_operation == Variant::OP_OR) {
		
		
		r_valid = true;
		GDScriptParser::DataType result;
		result.type_source = GDScriptParser::DataType::ANNOTATED_INFERRED;
		result.kind = GDScriptParser::DataType::BUILTIN;
		result.builtin_type = Variant::BOOL;
		return result;
	}
	Variant::Type a_type = p_a.builtin_type;
	Variant::Type b_type = p_b.builtin_type;
	if (p_a.kind == GDScriptParser::DataType::ENUM) {
		if (p_a.is_meta_type) {
			a_type = Variant::DICTIONARY;
		} else {
			a_type = Variant::INT;
		}
	}
	if (p_b.kind == GDScriptParser::DataType::ENUM) {