added asserts for focus and gaze provider.

Author: StephenHodgson

Assets/MixedRealityToolkit/InputSystem/Focus/FocusProvider.cs

@@ -228,6 +228,9 @@ private void Awake()
 
         private void Start()
         {
+            Debug.Assert(MixedRealityManager.IsInitialized, "No Mixed Reality Manager found in the scene.  Be sure to run the Mixed Reality Configuration.");
+            Debug.Assert(InputSystem != null, "No Input System found, Did you set it up in your configuration profile?");
+
             // Register the FocusProvider as a global listener to get input events.
             InputSystem.Register(gameObject);
         }

Assets/MixedRealityToolkit/InputSystem/Gaze/GazeProvider.cs

@@ -208,6 +208,9 @@ protected virtual void OnEnable()
 
         private void Start()
         {
+            Debug.Assert(MixedRealityManager.IsInitialized, "No Mixed Reality Manager found in the scene.  Be sure to run the Mixed Reality Configuration.");
+            Debug.Assert(InputSystem != null, "No Input System found, Did you set it up in your configuration profile?");
+
             if (cursorPrefab != null)
             {
                 var cursorObj = Instantiate(cursorPrefab, transform);