Add the stub applet instead of not implemented exception.

Ryujinx.HLE/HOS/Applets/AppletManager.cs

@@ -24,7 +24,7 @@ namespace Ryujinx.HLE.HOS.Applets
                 return (IApplet)Activator.CreateInstance(appletClass, system);
             }
 
-            throw new NotImplementedException($"{applet} applet is not implemented.");
+            return new StubApplet(applet);
         }
     }
 }

Ryujinx.HLE/HOS/Applets/StubApplet.cs

@@ -0,0 +1,48 @@
+using System;
+using Ryujinx.Common.Logging;
+using Ryujinx.HLE.HOS.Services.Am.AppletAE;
+
+namespace Ryujinx.HLE.HOS.Applets
+{
+    class StubApplet : IApplet
+    {
+        public AppletId AppletId { get; }
+
+        public event EventHandler AppletStateChanged;
+
+        public StubApplet(AppletId appletId)
+        {
+            AppletId = appletId;
+        }
+
+        public ResultCode GetResult()
+        {
+            Logger.PrintWarning(LogClass.ServiceAm, $"Stub {AppletId} applet called.");
+
+            return ResultCode.Success;
+        }
+
+        public ResultCode Start(AppletSession normalSession, AppletSession interactiveSession)
+        {
+            Logger.PrintWarning(LogClass.ServiceAm, $"Stub {AppletId} applet called.");
+
+            byte[] normalData;
+            byte[] interactiveData;
+
+            normalSession.TryPop(out normalData);
+            interactiveSession.TryPop(out interactiveData);
+
+            normalSession.Push(BuildResponse());
+            interactiveSession.Push(BuildResponse());
+
+            AppletStateChanged?.Invoke(this, null);
+
+            return ResultCode.Success;
+        }
+
+        private byte[] BuildResponse()
+        {
+            return new byte[0x1000];
+        }
+    }
+}