Occasionally we get a 400 error from the call to <our-app>.auth0.com during checkSession. This can be due to a temporary bad state on the client (eg. when changing which auth0 tenant we are using), or some other issue which is not that important and is cleared by logging in/out.
However, when this 400 response is returned, the callback to checkSession is not fired. It seems there is some code missing to handle this kind of error and I’m not sure how we can detect it; since it’s an async operation we can’t simply try/catch the checkSession call.