Use of `@subSchema` does not eagerly instantiate a `ModelSchema`

[mressler]

If, in the test code on line 842 of ts.ts, we did not add an @serializable annotation, the ModelSchema for PictureTodo would not be instantiated, getOrCreateSchema called from subSchema would return ToDo instead of PictureToDo and the invariant on the very next line would trigger, resulting in an Error: "Can not apply subSchema on a schema not extending another one.".

I think the lazy evaluation is assuming there will be an @serialize annotation on an intermediate subclass (like PictureToDo) which will trigger the createModelSchema call. However, in my use case, I have an intermediate class that does not provide additional properties for serialization.

[mressler]

If it's straightforward to get set up to contribute to the repo, I'd be happy to go through it. I feel like I have this one pinned down with a use case and a test case.

[mressler]

As a workaround, I add a dummy property to any @subSchema class that doesn't already have @serializable annotations, which forces the evaluation and the ModelSchema gets created.

[turien-pix4d]

Yes, that's unconvinient when you have subclasses that exist only for polymorphism i.e., the subclass have exactly the same data, but some behavior changes based on the "type" property of teh serialized data.

class Todo {
  @serializable
  id: string;

  @serializable
  text: string;

  sendReminder() {
    console.log(`Reminder: ${this.text}`);
  }
}

@subSchema("email")
class EmailTodo extends Todo {
  sendReminder() {
    sendEmail({
      dest: 'todo_reminder_list@mail.com'
      object: 'TODO',
      message: `Reminder: ${this.text}`
    });
  }
}


const ser = serialize(Object.assign(new EmailTodo(), {
  id: "pic1",
  text: "Lorem Ipsum",
}));
   
const deser = deserialize(Todo, ser);
deser.sendReminder() // will log "Reminder: Lorem Ipsum", which is incorrect, it should send an email instead