fix race condition dependent bug of loading feature toggles

[philippotto]

URL of deployed dev instance (used for testing):

• https://___.webknossos.xyz

Steps to test:

(I tested it quite thoroughly, but for the record...)

• if you want to make the bug reproducible, you can run yarn disable-autologin and change the getFeatureToggles function in admin_rest_api.js to

export async function getFeatureToggles(): Promise<APIFeatureToggles> {
  await Utils.sleep(5000);
  return Request.receiveJSON("/api/features");
}

• then, make sure you are not logged in and visit the dashboard
• using the code of this PR, the bug shouldn't occur anymore

Issues:

• fixes Race condition when loading api/features on app initialization #3157

---

• Updated changelog
• Ready for review

[daniel-wer]

LGTM, nice find! Was this causing the error when logging out sometimes?

[philippotto]

Was this causing the error when logging out sometimes?

Yes, I assume so :)