### 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
#ifdef DEBUG_ENABLED
	print_verbose("GDScript: Reloading all scripts");
	List<Ref<GDScript>> scripts;
	{
		MutexLock lock(this->mutex);
		SelfList<GDScript> *elem = script_list.first();
		while (elem) {
			
			if (elem->self()->is_root_script() && elem->self()->get_path().is_resource_file()) {
				print_verbose("GDScript: Found: " + elem->self()->get_path());
				scripts.push_back(Ref<GDScript>(elem->self())); 
			}
			elem = elem->next();
		}
	}
	
	scripts.sort_custom<GDScriptDepSort>(); 
	for (Ref<GDScript> &scr : scripts) {
		print_verbose("GDScript: Reloading: " + scr->get_path());
		scr->load_source_code(scr->get_path());
		scr->reload(true);
	}
#endif
}
void GDScriptLanguage::reload_tool_script(const Ref<Script> &p_script, bool p_soft_reload) {