### Godot version

4.0.beta10

### System information

Windows 11

### Issue description
UPDATE: This problem only occurs when the source code contains inner classes

Before 4.0.Beta9, I could get a GDScript instance by `GDScript.new()` and then set the `source_code` property and then `reload()`, but now it throws an error 
```
USER SCRIPT ERROR: Parse Error: Could not find script "".
   at: GDScript::reload (built-in:1644)
```
In my software, I use the above method when the user modifies the code text, and then read the godot log to implement real-time error checking of the custom user script editor. But now this functionality is completely broken

### Steps to reproduce

1. Create a GDScript instance by `GDScript.new()`
2. set the `source_code` property and then `reload()`

### Minimal reproduction project

N/A
String first = p_qualified_name.get_slice("::", 0);
	Vector<String> class_names;
	GDScript *result = nullptr;
	
	if (first.is_empty() || first == name) {
		class_names = p_qualified_name.split("::");
		result = this;
	} else if (p_qualified_name.begins_with(get_root_script()->path)) {
		
		class_names = p_qualified_name.trim_prefix(get_root_script()->path).split("::");
		result = get_root_script();
	} else if (HashMap<StringName, Ref<GDScript>>::Iterator E = subclasses.find(first)) {
		class_names = p_qualified_name.split("::");
		result = E->value.ptr();
	} else if (_owner != nullptr) {
		
		return _owner->find_class(p_qualified_name);