title: Unity5.6 Collision2D contact points array index out of range error
body: <p>When I updated my Unity version 5.5 to 5.6, an error occured about the Collision2D.contacts array. When I try to access the contacts array, I can not get contact point info now.</p>
  
  <pre><code>    void OnCollisionExit2D(Collision2D col)
      {
       if (col.gameObject.CompareTag("Ground")) 
       {
               if ((_transform.position.y - col.contacts[0].point.y) &gt; colliderHeight / 2 + .15f) 
               {
                   Debug.Log ("Contact count = " + col.contacts.Length);
                   _onGround = false;
                   ParticleController.PlayDustEffect ();
               }
  
           }
       }
  </code></pre>
  
  <p>Error Log : </p>
  
  <blockquote>
    <p>IndexOutOfRangeException: Array index is out of range. 
    Player.OnCollisionExit2D (UnityEngine.Collision2D col) (at Assets/Scripts/CharacterController/Player.cs:759)</p>
  </blockquote>
  
  <p>How can I fix the error?</p>
  
  <p>Thanks for your time.</p>