GetGamepad no longer throws if slot is empty

src/Input/Gamepad.cs

@@ -33,6 +33,8 @@ namespace MoonWorks.Input
 		public Trigger TriggerLeft { get; } = new Trigger();
 		public Trigger TriggerRight { get; } = new Trigger();
 
+		public bool IsDummy => Handle == IntPtr.Zero;
+
 		private Dictionary<SDL.SDL_GameControllerButton, Button> EnumToButton;
 		private Dictionary<SDL.SDL_GameControllerAxis, Axis> EnumToAxis;
 		private Dictionary<SDL.SDL_GameControllerAxis, Trigger> EnumToTrigger;
@@ -76,6 +78,8 @@ namespace MoonWorks.Input
 		}
 
 		internal void Update()
+		{
+			if (!IsDummy)
 			{
 				foreach (var (sdlEnum, button) in EnumToButton)
 				{
@@ -96,6 +100,7 @@ namespace MoonWorks.Input
 					trigger.Update(axisValue);
 				}
 			}
+		}
 
 		/// <summary>
 		/// Sets vibration values on the left and right motors.

src/Input/Input.cs

@@ -1,15 +1,16 @@
 using SDL2;
 using System;
-using System.Collections.Generic;
 
 namespace MoonWorks.Input
 {
 	public class Inputs
 	{
+		public const int MAX_GAMEPADS = 4;
+
 		public Keyboard Keyboard { get; }
 		public Mouse Mouse { get; }
 
-		List<Gamepad> gamepads = new List<Gamepad>();
+		Gamepad[] gamepads;
 
 		public static event Action<char> TextInput;
 
@@ -18,11 +19,17 @@ namespace MoonWorks.Input
 			Keyboard = new Keyboard();
 			Mouse = new Mouse();
 
-			for (int i = 0; i < SDL.SDL_NumJoysticks(); i++)
+			gamepads = new Gamepad[MAX_GAMEPADS];
+
+			for (var i = 0; i < 4; i += 1)
 			{
 				if (SDL.SDL_IsGameController(i) == SDL.SDL_bool.SDL_TRUE)
 				{
-					gamepads.Add(new Gamepad(SDL.SDL_GameControllerOpen(i)));
+					gamepads[i] = new Gamepad(SDL.SDL_GameControllerOpen(i));
+				}
+				else
+				{
+					gamepads[i] = new Gamepad(IntPtr.Zero);
 				}
 			}
 		}
@@ -41,7 +48,7 @@ namespace MoonWorks.Input
 
 		public bool GamepadExists(int slot)
 		{
-			return slot < gamepads.Count;
+			return !gamepads[slot].IsDummy;
 		}
 
 		public Gamepad GetGamepad(int slot)