Add placeholders

Shared/Views/ContentItemView.swift

@@ -11,8 +11,10 @@ struct ContentItemView: View {
                 ChannelPlaylistCell(playlist: item.playlist)
             case .channel:
                 ChannelCell(channel: item.channel)
-            default:
+            case .video:
                 VideoCell(video: item.video)
+            default:
+                PlaceholderCell()
             }
         }
     }

Shared/Views/PlaceholderCell.swift

@@ -0,0 +1,16 @@
+import Defaults
+import SwiftUI
+
+struct PlaceholderCell: View {
+    var body: some View {
+        VideoCell(video: .fixture)
+            .redacted(reason: .placeholder)
+    }
+}
+
+struct PlaceholderCell_Previews: PreviewProvider {
+    static var previews: some View {
+        PlaceholderCell()
+            .injectFixtureEnvironmentObjects()
+    }
+}