MobX - Cannot obtain atom from undefined after migrate to MobX v.6+

Question

I need to migrate MobX v.5 to MobX v6+ which supports react hooks, however after upgrading to MobX v6+ I get this error [MobX] Cannot obtain atom from undefined I was able to track down that when I want to create Lazy observable with onBecomeObserved, this throws error above for some reason, but I cannot figure out what cause this.

I use inject which is available from MobX to connect components to stores, it might not be a good pattern anymore, but its the fastest way for me how to migrate from old MobX. withTheme function is Material-UI connector to theme system

export function injector<T>(target: T): T {
  return inject('data', 'view')(withTheme(target));
}

export function storeConnect<T extends IReactComponent>(target: T): T {
  return injector(observer(target));
}

Here is base store where I create lazy observable which should take care of loading data from API, however here my app crash and cant find out working solution to this.

abstract class BaseProvider {
  @observable state = "NONE";

  constructor() {
    //this it throws error
    onBecomeObserved(this, "isLoading", this.loadData);
  }

  public abstract loadData(): void;

  @computed get isLoading() {
    return (this.state === "Loading");
  }
}

class Provider extends BaseProvider {
  constructor() {
    super();
    this.loadData = this.loadData.bind(this);
  }

  public loadData() {
    if (this.state !== "Loaded") {
      //some code
    }
  }
}