### 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
return script;
}
ScriptLanguage *GDScriptInstance::get_language() {
	return GDScriptLanguage::get_singleton();
}
const Variant GDScriptInstance::get_rpc_config() const {
	return script->get_rpc_config();
}
void GDScriptInstance::reload_members() {
#ifdef DEBUG_ENABLED
	Vector<Variant> new_members;
	new_members.resize(script->member_indices.size());
	
	for (KeyValue<StringName, GDScript::MemberInfo> &E : script->member_indices) {
		if (member_indices_cache.has(E.key)) {
			Variant value = members[member_indices_cache[E.key]];
			new_members.write[E.value.index] = value;
		}
	}
	members.resize(new_members.size()); 
	
	members = new_members;
	
	member_indices_cache.clear();
	for (const KeyValue<StringName, GDScript::MemberInfo> &E : script->member_indices) {
		member_indices_cache[E.key] = E.value.index;
	}
#endif
}
GDScriptInstance::GDScriptInstance() {