Reviews are accessible even if vocabulary is not yet loaded

[VadimGush]

In vocabulary section we have review for WaniKani vocabulary. It is not available if user is not logged into WaniKani account. Which is expected, because Kazan doesn't have any data to generate those reviews. But! When user is logged in, it takes some time for web-app to load vocabulary data from WaniKani. But at this moment WaniKani vocabulary review is already available. Of course, if user will start that review while application is trying to load data from WaniKani, user will get an error (or some other type of failure). We want to avoid that.

So, what should we do: if a certain review depends on the data from WaniKani, it shouldn't be available before all data is loaded.