SettingsView needs to check if Repository is null

The SettingsView is one of the few Views that needs to check for
Repository being null. As it is used in the "Initialize Repository"
workflow.

Author: StanleyGoldman

src/UnityExtension/Assets/Editor/GitHub.Unity/UI/SettingsView.cs

@@ -51,8 +51,12 @@ public override void OnEnable()
             userSettingsView.OnEnable();
             AttachHandlers(Repository);
 
-            Repository.CheckCurrentRemoteChangedEvent(lastCurrentRemoteChangedEvent);
-            Repository.CheckLocksChangedEvent(lastLocksChangedEvent);
+            if (Repository != null)
+            {
+                Repository.CheckCurrentRemoteChangedEvent(lastCurrentRemoteChangedEvent);
+                Repository.CheckLocksChangedEvent(lastLocksChangedEvent);
+            }
+
             metricsHasChanged = true;
         }