Task groups don't work with glimmer components

[jrjohnson]

I don't know if this belongs here or in the ember-concurrency repo.

Using a taskGroup with a glimmer component throws obj.get is not a function. Comes from here where EmberObject expects get to exist.

import Component from '@glimmer/component';
import { task, taskGroup } from 'ember-concurrency-decorators';

export default class SimpleChart extends Component {
  @taskGroup
  someGroup;
  @task({ group: 'someGroup' })
  *doSomething() {

  }
}

[buschtoens]

Fixed via https://github.com/machty/ember-concurrency/pull/321.

Thanks @jrjohnson!