Fix crash upon split view expansion before sidebar VC is loaded

Tusker/Screens/Main/MainSidebarViewController.swift

@@ -95,6 +95,8 @@ class MainSidebarViewController: UIViewController {
     }
     
     func select(item: Item, animated: Bool) {
+        // ensure view is loaded, since dataSource is created in viewDidLoad
+        loadViewIfNeeded()
         guard let indexPath = dataSource.indexPath(for: item) else { return }
         collectionView.selectItem(at: indexPath, animated: animated, scrollPosition: .top)
         itemLastSelectedTimestamps[item] = Date()