Add player joining

In the platformer scene, whenever you connect a new keyboard or controller, or interact with one already connected, a new player will be created and tied to that input device. Please try to break this system to make sure it works properly.

Assets/Games/Platformer/PlatformerCameraMovement.cs

@@ -17,6 +17,8 @@ public class PlatformerCameraMovement : MonoBehaviour
 
     private void Update()
     {
+        if (players.Count == 0) return;
+
         Vector3 playerAverage = Vector3.zero;
         foreach (GameObject player in players)
         {