I think this is no particular issue with the updater component, but a generic problem with how the lovelace UI handles non existing entities.
There are various entities that are only dynamically created while HA is running. For example HTTP sensors or some auto discovered entities. For example I have a media player that isn’t always online, thus not always discovered on HA startup. Every time I open the view in which this entity is configured in the browser, a similar Uncaught TypeError is thrown in the log together with a yellow “Entity not available” box in the UI:
And updater.updater also doesn’t exist until there is an update available, causing these errors as well.
While the classic UI more or less ignores non-existing entities configured in a view, lovelace throws an error every time it wants to display a non existent entity in a view. I don’t know, why it shows that yellow box for media players, but not for the updater entity, but the errors in the log are similar.
ATM I’m not aware of any mechanism in the lovelace UI to properly deal with only temporary existing entities.