### 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
profiling = false;
	script_frame_time = 0;
	_debug_call_stack_pos = 0;
	int dmcs = GLOBAL_DEF(PropertyInfo(Variant::INT, "debug/settings/gdscript/max_call_stack", PROPERTY_HINT_RANGE, "512," + itos(GDScriptFunction::MAX_CALL_DEPTH - 1) + ",1"), 1024);
	if (EngineDebugger::is_active()) {
		
		_debug_max_call_stack = dmcs;
		_call_stack = memnew_arr(CallLevel, _debug_max_call_stack + 1);
	} else {
		_debug_max_call_stack = 0;
		_call_stack = nullptr;
	}
#ifdef DEBUG_ENABLED
	GLOBAL_DEF("debug/gdscript/warnings/enable", true);
	GLOBAL_DEF("debug/gdscript/warnings/exclude_addons", true);
	for (int i = 0; i < (int)GDScriptWarning::WARNING_MAX; i++) {
		GDScriptWarning::Code code = (GDScriptWarning::Code)i;
		Variant default_enabled = GDScriptWarning::get_default_value(code);
		String path = GDScriptWarning::get_settings_path_from_code(code);
		GLOBAL_DEF(GDScriptWarning::get_property_info(code), default_enabled);
	}
#endif 
}
GDScriptLanguage::~GDScriptLanguage() {
	singleton = nullptr;
}
void GDScriptLanguage::add_orphan_subclass(const String &p_qualified_name, const ObjectID &p_subclass) {
	orphan_subclasses[p_qualified_name] = p_subclass;
}
Ref<GDScript> GDScriptLanguage::get_orphan_subclass(const String &p_qualified_name) {