don't log signalr heartbeat exceptions as EPIC FAIL.

NzbDrone.Common/Instrumentation/GlobalExceptionHandlers.cs

@@ -21,6 +21,15 @@ namespace NzbDrone.Common.Instrumentation
 
         private static void AppDomainException(Exception exception)
         {
+            if (exception == null) return;
+
+            if (exception is NullReferenceException &&
+                exception.ToString().Contains("Microsoft.AspNet.SignalR.Transports.TransportHeartbeat.ProcessServerCommand"))
+            {
+                Logger.Warn("SignalR Heartbeat error.");
+                return;
+            }
+
             Console.WriteLine("EPIC FAIL: {0}", exception);
             Logger.FatalException("EPIC FAIL: " + exception.Message, exception);
         }