fix(ember): use _backburner if it exists

[pbernery]

run.backburner is deprecated and creates errors now when used and when ember-cli-deprecation-workflow is in your dependencies.

This commit fixes the issue by using the _backburner if it exists (which is the case in recent versions of Ember), or run.backbackburner if not (which is the case in older versions of Ember). Thus, run.backburner is not called if _backburner is present and thus does not create a deprecation warning.

This fixes the issue reported here event after the PR was merged.

[AbhiPrasad]

Thanks for the PR - appreciate the help :)

We have some Next 12 tests failing on master that we are looking to fix, so you can ignore those for now!

[AbhiPrasad]

With this change not all code paths here will return a value - so getBackburner() might return undefined now. Can we get around this somehow? Or do we have to do larger refactors for the usage of the getBackburner function?

This is why https://github.com/getsentry/sentry-javascript/runs/5235458452?check_suite_focus=true is failing.

[pbernery]

That's a good point. I am not knowledgable enough in the history of Ember, but I believe that if _backburner does not exist, it means we are on an older version of Ember and thus run.backburner exists. We could thus remove the condition around run.backburner.

[AbhiPrasad]

@k-fish may be able to help us here

[AbhiPrasad]

Hey, please rebase this branch as we’ve fixed the test failures on master.

[pbernery]

I updated the code by always returning a value, and rebased to the latest master as asked.

[AbhiPrasad]

Seems like this is still failing CI as run.backburner can be undefined.

[k-fish]

Just took a look, and agree that _backburner should be first so newer Ember versions won't be using the old way of accessing it. We'd likely want to stay defensive here since we really don't want Sentry to be the cause of breaking someones app in an initializer on any version of Ember.

On that note, I'd keep the undefined check, and make a simple empty mock object that matches the usage, something like this:

function getBackburner(): Pick<ExtendedBackburner, 'on' | 'off'> {
  if (_backburner) {
    return _backburner;
  }

  if (run.backburner) {
    return run.backburner;
  }

  return {
    on() {},
    off() {},
  };
}

[pbernery]

@k-fish I followed your feedback and return a mock in the final case.