Remove requirement for service provider to be returned in ConfigureServices

None of the .NET core docs reference this, and it is only needed for this one check.

See reactjs#601

Author: Dustin Masters

src/React.AspNet.Middleware/ReactBuilderExtensions.cs

@@ -3,7 +3,7 @@
  *  All rights reserved.
  *
  *  This source code is licensed under the BSD-style license found in the
- *  LICENSE file in the root directory of this source tree. An additional grant 
+ *  LICENSE file in the root directory of this source tree. An additional grant
  *  of patent rights can be found in the PATENTS file in the same directory.
  */
 
@@ -40,12 +40,10 @@ public static IApplicationBuilder UseReact(
 			BabelFileOptions fileOptions = null
 		)
 		{
-			EnsureServicesRegistered(app);
-
 			RegisterAspNetServices(React.AssemblyRegistration.Container, app.ApplicationServices);
 
 			Initializer.Initialize(registerOptions => AsPerRequestSingleton(
-				app.ApplicationServices.GetService<IHttpContextAccessor>(), 
+				app.ApplicationServices.GetService<IHttpContextAccessor>(),
 				registerOptions
 			));
 
@@ -79,19 +77,6 @@ TinyIoCContainer.RegisterOptions registerOptions
 			);
 		}
 
-		/// <summary>
-		/// Ensures React services have been registered in the ASP.NET dependency injection container.
-		/// </summary>
-		/// <param name="app">ASP.NET application builder</param>
-		private static void EnsureServicesRegistered(IApplicationBuilder app)
-		{
-			var registrations = app.ApplicationServices.GetService<HttpContextLifetimeProvider.PerRequestRegistrations>();
-			if (registrations == null)
-			{
-				throw new ReactNotInitialisedException("Please call services.AddReact() before app.UseReact().");
-			}
-		}
-
 		/// <summary>
 		/// Registers required ASP.NET services in ReactJS.NET's TinyIoC container. This is used
 		/// for ASP.NET services that are required by ReactJS.NET.

src/React.Sample.Webpack.CoreMvc/Startup.cs

@@ -20,7 +20,7 @@ public Startup(IConfiguration configuration)
 		public IConfiguration Configuration { get; }
 
 		// This method gets called by the runtime. Use this method to add services to the container.
-		public IServiceProvider ConfigureServices(IServiceCollection services)
+		public void ConfigureServices(IServiceCollection services)
 		{
 			services.AddMvc();
 
@@ -31,7 +31,7 @@ public IServiceProvider ConfigureServices(IServiceCollection services)
 			services.AddSingleton<IHttpContextAccessor, HttpContextAccessor>();
 
 			// Build the intermediate service provider then return it
-			return services.BuildServiceProvider();
+			services.BuildServiceProvider();
 		}
 
 		// This method gets called by the runtime. Use this method to configure the HTTP request pipeline.