Add missing service.

Author: pawchen

converter/generator/Program.cs

@@ -71,6 +71,7 @@ async static Task Main(string[] cmdArgs)
             services.AddTransient<IDocTransformer, DocBookTransformer>();
         }
 
+        services.AddSingleton<DocTransformerArgs>(sp => sp.GetRequiredService<DocToStaticPagesTransformerArgs>());
         services.AddSingleton<ProblemRecorder>();
 
         var serviceProvider = services.BuildServiceProvider();