Simple Mobile Placeholder throws NullReferenceException when ran as is

I’m following the manual for the Simple Mobile Placeholder. However, when I ran it first time (even before setting up Android SDK), it spits a lot of “NullReferenceException” when I hover and move cursor over the cube. Thus, clicking on the cube doesn’t work at all.
Here’s the error message and a backtrace, where it can be seen that the problem originates in “PhysicsRaycaster.cs”:

NullReferenceException: Object reference not set to an instance of an object
UnityEngine.EventSystems.PhysicsRaycaster.Raycast (UnityEngine.EventSystems.PointerEventData eventData, System.Collections.Generic.List`1 resultAppendList) (at /Users/builduser/buildslave/unity/build/Extensions/guisystem/UnityEngine.UI/EventSystem/Raycasters/PhysicsRaycaster.cs:133)
UnityEngine.EventSystems.EventSystem.RaycastAll (UnityEngine.EventSystems.PointerEventData eventData, System.Collections.Generic.List`1 raycastResults) (at /Users/builduser/buildslave/unity/build/Extensions/guisystem/UnityEngine.UI/EventSystem/EventSystem.cs:188)
UnityEngine.EventSystems.PointerInputModule.GetMousePointerEventData (Int32 id) (at /Users/builduser/buildslave/unity/build/Extensions/guisystem/UnityEngine.UI/EventSystem/InputModules/PointerInputModule.cs:207)
UnityEngine.EventSystems.StandaloneInputModule.ProcessMouseEvent (Int32 id) (at /Users/builduser/buildslave/unity/build/Extensions/guisystem/UnityEngine.UI/EventSystem/InputModules/StandaloneInputModule.cs:447)
UnityEngine.EventSystems.StandaloneInputModule.ProcessMouseEvent () (at /Users/builduser/buildslave/unity/build/Extensions/guisystem/UnityEngine.UI/EventSystem/InputModules/StandaloneInputModule.cs:433)
UnityEngine.EventSystems.StandaloneInputModule.Process () (at /Users/builduser/buildslave/unity/build/Extensions/guisystem/UnityEngine.UI/EventSystem/InputModules/StandaloneInputModule.cs:212)
UnityEngine.EventSystems.EventSystem.Update () (at /Users/builduser/buildslave/unity/build/Extensions/guisystem/UnityEngine.UI/EventSystem/EventSystem.cs:285)

Not quite sure what shall I do with this problem. Any ideas?
I’m quite new to Unity, and not sure why mouse tracking crashes on a sample project, distributed by Unity. Here’s the only script I have so far (in Scripts folder of Project tab):

using UnityEngine;
using System.Collections;

public class SpinningCube : MonoBehaviour 
{
	public float m_Speed = 20f;

	private Vector3 m_RotationDirection = Vector3.up;

	public void ToggleRotationDirection()
	{
		Debug.Log ("Toggling rotation direction");

		if (m_RotationDirection == Vector3.up) 
		{
			m_RotationDirection = Vector3.down;
		}
		else 
		{
			m_RotationDirection = Vector3.up;
		}
	}

	void Update() 
	{
		transform.Rotate(m_RotationDirection * Time.deltaTime * m_Speed);
	}

	public void OnMouseOver() {
		
	}
}

As can be seen, it has nothing to do with mouse tracking. Thus, I suspect, it’s an internal issue with my Unity installation (if that makes any sense).
My platform is macOS Sierra 10.12.5, Unity 2017.2.0b2

I downloaded Unity 2017.1.0f3 (not beta) and it worked with no problems.