### 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
p_extensions->push_back("gd");
}
bool ResourceFormatLoaderGDScript::handles_type(const String &p_type) const {
	return (p_type == "Script" || p_type == "GDScript");
}
String ResourceFormatLoaderGDScript::get_resource_type(const String &p_path) const {
	String el = p_path.get_extension().to_lower();
	if (el == "gd") {
		return "GDScript";
	}
	return "";
}
void ResourceFormatLoaderGDScript::get_dependencies(const String &p_path, List<String> *p_dependencies, bool p_add_types) {
	Ref<FileAccess> file = FileAccess::open(p_path, FileAccess::READ);
	ERR_FAIL_COND_MSG(file.is_null(), "Cannot open file '" + p_path + "'.");
	String source = file->get_as_utf8_string();
	if (source.is_empty()) {
		return;
	}
	GDScriptParser parser;
	if (OK != parser.parse(source, p_path, false)) {
		return;
	}
	for (const String &E : parser.get_dependencies()) {
		p_dependencies->push_back(E);
	}
}
Error ResourceFormatSaverGDScript::save(const Ref<Resource> &p_resource, const String &p_path, uint32_t p_flags) {