### Godot version

v4.0.beta17.official [c40020513]

### System information

Apple M1 Max - macOS Ventura 13.1 (22C65)

### Issue description

I am getting an error due to functions no longer returning the correct typed array, when the function concatenates arrays and returns it.

In other words, the following fails:

```
func add_arrays() -> Array[ClassA]:
	var array_1: Array[ClassA] = []
	var array_2: Array[ClassA] = []
	return array_1 + array_2
```

<img width="864" alt="Screenshot 2023-02-02 at 1 02 53 PM" src="https://user-images.githubusercontent.com/905216/216320503-475bf4a1-353e-455c-87d5-69d036db706c.png">

I'm assuming when concatenating, the typing changes to a generic `Array` now? Just a guess. 

### Steps to reproduce

N/A

### Minimal reproduction project

[Godot Crash Project.zip](https://github.com/godotengine/godot/files/10568780/Godot.Crash.Project.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) {