UserCanceled error thrown when trying to access an unexisting providerId with the QML Setup element

How to reproduce:

Add the following to your application:

Setup {
    id: setup
    applicationId: "YOUR APP ID HERE"
    providerId: "asdf"
}

and call setup.exec().

When having debugging enabled as described in https://developer.ubuntu.com/en/start/platform/guides/online-accounts-developer-guide/, the following error can be found in the logs:

RequestAccess failed: QDBusError("com.ubuntu.OnlineAccountsUi.UserCanceled", "Canceled")

I spent hours trying to find the reason for that error as it does not at all hint you at what you actually have done wrong. I think there should be a more specific error message here.