### 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
if (has_method(CoreStringNames::get_singleton()->_to_string)) {
		Callable::CallError ce;
		Variant ret = callp(CoreStringNames::get_singleton()->_to_string, nullptr, 0, ce);
		if (ce.error == Callable::CallError::CALL_OK) {
			if (ret.get_type() != Variant::STRING) {
				if (r_valid) {
					*r_valid = false;
				}
				ERR_FAIL_V_MSG(String(), "Wrong type for " + CoreStringNames::get_singleton()->_to_string + ", must be a String.");
			}
			if (r_valid) {
				*r_valid = true;
			}
			return ret.operator String();
		}
	}
	if (r_valid) {
		*r_valid = false;
	}
	return String();
}
Ref<Script> GDScriptInstance::get_script() const {