How to prevent double tap + firebase?

Question

Android

I implement the entrance to the application through firebase (all work with data in the ViewModel), I use NavController for navigation. Double click problem, when I press the login button and immediately (quickly) the register button, it crashes (Navigation action/destination cannot be found from the current destination).

I found an article https://stackoverflow.com/questions/51060762/illeg...
, which describes the solution, but in my case it can take more than a second or less between clicks, it all depends on the response from the database.

I made a function that blocks all buttons when you click on one until the end of the operation in the coroutine.
I pass a function from the fragment class to a function parameter from the view model, which calls a function from the model where the data is taken from the firebase, at the end of the download I turn on the buttons with that function, if it was not possible to enter, if I succeeded, then I start the navigation, after which I turn on the buttons

What will be more right?