another improvement

Pilz.Net/Api/ApiServer.cs

@@ -280,17 +280,12 @@ public class ApiServer : IApiServer
         if (AllowMultipleRequests)
             Receive();
 
-        // Cancel if we don't have a context
-        if (context is null)
-        {
-            FreeSlot();
-            return;
-        }
-
         // Check context
+        var success = false;
+        if (context is not null)
+        {
             Log.Info("Request retrived for " + context.Request.RawUrl);
             OnCheckContext?.Invoke(this, new(context));
-        var success = false;
             try
             {
                 CheckContext(context);
@@ -306,13 +301,14 @@ public class ApiServer : IApiServer
             {
                 OnCheckContextCompleted?.Invoke(this, new(context));
             }
+        }
 
         // Try closing the request on fail
         if (!success)
         {
             try
             {
-                context.Response.Close();
+                context?.Response.Close();
             }
             catch (Exception)
             {