### Godot version

4.1.dev

### System information

Win11

### Issue description

I load a non-existing GDScript, but it still returns a valid instance instead of null.
```gdscript
@tool
extends EditorScript

func _run():
	var s = ResourceLoader.load("non_exists.gd", "", ResourceLoader.CACHE_MODE_IGNORE)
	print(s)
	assert(s == null)

```

```
  Attempt to open script 'res://non_exists.gd' resulted in error 'File not found'.
<GDScript#-9223369015982753437>
  res://new_script.gd:7 - Assertion failed.

```

### Steps to reproduce

N/A

### Minimal reproduction project

N/A
if (p_name == GDScriptLanguage::get_singleton()->strings._script_source) {
		set_source_code(p_value);
		reload();
	} else {
		const GDScript *top = this;
		while (top) {
			HashMap<StringName, MemberInfo>::ConstIterator E = static_variables_indices.find(p_name);
			if (E) {
				const GDScript::MemberInfo *member = &E->value;
				Variant value = p_value;
				if (member->data_type.has_type && !member->data_type.is_type(value)) {
					const Variant *args = &p_value;
					Callable::CallError err;
					Variant::construct(member->data_type.builtin_type, value, &args, 1, err);
					if (err.error != Callable::CallError::CALL_OK || !member->data_type.is_type(value)) {
						return false;
					}
				}
				if (member->setter) {
					const Variant *args = &value;
					Callable::CallError err;
					callp(member->setter, &args, 1, err);
					return err.error == Callable::CallError::CALL_OK;
				} else {
					static_variables.write[member->index] = value;
					return true;
				}
			}
			top = top->_base;