Addressing recently introduced warnings

Author: fabiocav

src/DotNetWorker.Core/Context/Features/InvocationFeatures.cs

@@ -31,7 +31,7 @@ public InvocationFeatures(IEnumerable<IInvocationFeatureProvider> featureProvide
                 }
             }
 
-            return (T)feature;
+            return feature is null ? default : (T)feature;
         }
 
         public IEnumerator<KeyValuePair<Type, object>> GetEnumerator()

src/DotNetWorker.Core/Context/FunctionContextLoggerExtensions.cs

@@ -18,7 +18,7 @@ public static class FunctionContextLoggerExtensions
         /// <returns>The <see cref="ILogger{T}"/>.</returns>
         public static ILogger<T> GetLogger<T>(this FunctionContext context)
         {
-            return context.InstanceServices.GetService<ILogger<T>>();
+            return context.InstanceServices.GetService<ILogger<T>>()!;
         }
 
         /// <summary>
@@ -30,7 +30,7 @@ public static ILogger<T> GetLogger<T>(this FunctionContext context)
         public static ILogger GetLogger(this FunctionContext context, string categoryName)
         {
             return context.InstanceServices
-                   .GetService<ILoggerFactory>()
+                   .GetService<ILoggerFactory>()!
                    .CreateLogger(categoryName);
         }
     }

src/DotNetWorker.Grpc/GrpcServiceCollectionExtensions.cs

@@ -1,6 +1,7 @@
 // Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the MIT License. See License.txt in the project root for license information.
 
+using System;
 using System.Threading.Channels;
 using Grpc.Core;
 using Grpc.Net.Client;
@@ -47,7 +48,9 @@ public static IServiceCollection AddGrpc(this IServiceCollection services)
             services.AddSingleton<IWorker, GrpcWorker>();
             services.AddSingleton<FunctionRpcClient>(p =>
             {
-                IOptions<GrpcWorkerStartupOptions> argumentsOptions = p.GetService<IOptions<GrpcWorkerStartupOptions>>();
+                IOptions<GrpcWorkerStartupOptions> argumentsOptions = p.GetService<IOptions<GrpcWorkerStartupOptions>>()
+                    ?? throw new InvalidOperationException("gRPC Serivces are not correctly registered.");
+
                 GrpcWorkerStartupOptions arguments = argumentsOptions.Value;
 
                 GrpcChannel grpcChannel = GrpcChannel.ForAddress($"http://{arguments.Host}:{arguments.Port}", new GrpcChannelOptions()