Null pointer check added for subscription as 2nd param is false.

Emby.Dlna/Eventing/EventManager.cs

@@ -31,7 +31,8 @@ namespace Emby.Dlna.Eventing
         public EventSubscriptionResponse RenewEventSubscription(string subscriptionId, string notificationType, string requestedTimeoutString, string callbackUrl)
         {
             var subscription = GetSubscription(subscriptionId, false);
-
+            if (subscription != null)
+            {
                 subscription.TimeoutSeconds = ParseTimeout(requestedTimeoutString) ?? 300;
                 int timeoutSeconds = subscription.TimeoutSeconds;
                 subscription.SubscriptionTime = DateTime.UtcNow;
@@ -45,6 +46,13 @@ namespace Emby.Dlna.Eventing
                 return GetEventSubscriptionResponse(subscriptionId, requestedTimeoutString, timeoutSeconds);
             }
 
+            return new EventSubscriptionResponse
+            {
+                Content = string.Empty,
+                ContentType = "text/plain"
+            };
+        }
+
         public EventSubscriptionResponse CreateEventSubscription(string notificationType, string requestedTimeoutString, string callbackUrl)
         {
             var timeout = ParseTimeout(requestedTimeoutString) ?? 300;