Why is there an error when the user loads the UI during a database refresh, when some plugins are still being compiled?

[Apollo3zehn]

Context from #116:

[QUESTION] We should check out the method RefreshDatabaseAsync in line 29: In line 51 you make an assignment to refreshDatabaseTask but it appears that the variable is not used anymore after that. Is refreshDatabaseTask a reference to AppState.ReloadPackagesTask?

I think I did this out of fear that the task being assigned to refreshDatabaseTask could be garbage collected if I do not assign it to a variable. But I read somewhere that tasks are never garbage collected and run until their end. I need to think about this more and would like to move it to an extra issue as this is unrelated to this PR. The reason an extra issue is needed is because Nexus throws exceptions when the database is being refreshed and the user loads the UI before the refresh task completed. This happens frequently when a new plugin version is being cloned and compile as this takes a few seconds. The original design idea of this method was to ensure that the old database is being used until the new one is ready and no exceptions should be thrown. But somehow this does not work properly.