[BACKPORT #6497] Fix of PVS-Studio warnings. (#6521)

* [BACKPORT #6497] Fix of PVS-Studio warnings.

(cherry-picked from f92c609)

* Revert new language features

---------

Co-authored-by: Sergey Popov <[email protected]>

Author: Arkatufus

src/core/Akka.Tests/Util/Base64EncodingSpec.cs

@@ -0,0 +1,29 @@
+// //-----------------------------------------------------------------------
+// // <copyright file="Base64EncodingSpec.cs" company="Akka.NET Project">
+// //     Copyright (C) 2009-2023 Lightbend Inc. <http://www.lightbend.com>
+// //     Copyright (C) 2013-2023 .NET Foundation <https://github.com/akkadotnet/akka.net>
+// // </copyright>
+// //-----------------------------------------------------------------------
+
+using Akka.Util;
+using Xunit;
+
+namespace Akka.Tests.Util
+{
+    public class Base64EncodingSpec
+    {
+        [Fact]
+        public void When_prefix_is_null_it_should_work_correctly()
+        {
+            var actual = Base64Encoding.Base64Encode(12345, (string)null);
+            Assert.Equal("5ad", actual);
+        }
+    
+        [Fact]
+        public void Should_calculate_base_64_correctly()
+        {
+            var actual = Base64Encoding.Base64Encode(12345, "");
+            Assert.Equal("5ad", actual);
+        }
+    }
+}

src/core/Akka/Actor/ActorCell.FaultHandling.cs

@@ -58,30 +58,27 @@ private void FaultRecreate(Exception cause)
                 if (System.Settings.DebugLifecycle)
                     Publish(new Debug(_self.Path.ToString(), failedActor.GetType(), "Restarting"));
 
-                if(!(failedActor is null))
+                var optionalMessage = CurrentMessage;
+                try
                 {
-                    var optionalMessage = CurrentMessage;
-                    try
-                    {
-                        // if the actor fails in preRestart, we can do nothing but log it: it’s best-effort
-                        failedActor.AroundPreRestart(cause, optionalMessage);
+                    // if the actor fails in preRestart, we can do nothing but log it: it’s best-effort
+                    failedActor.AroundPreRestart(cause, optionalMessage);
 
-                        // run actor pre-incarnation plugin pipeline
-                        var pipeline = _systemImpl.ActorPipelineResolver.ResolvePipeline(failedActor.GetType());
-                        pipeline.BeforeActorIncarnated(failedActor, this);
-                    }
-                    catch (Exception e)
-                    {
-                        HandleNonFatalOrInterruptedException(() =>
-                        {
-                            var ex = new PreRestartException(_self, e, cause, optionalMessage);
-                            Publish(new Error(ex, _self.Path.ToString(), failedActor.GetType(), e.Message));
-                        });
-                    }
-                    finally
+                    // run actor pre-incarnation plugin pipeline
+                    var pipeline = _systemImpl.ActorPipelineResolver.ResolvePipeline(failedActor.GetType());
+                    pipeline.BeforeActorIncarnated(failedActor, this);
+                }
+                catch (Exception e)
+                {
+                    HandleNonFatalOrInterruptedException(() =>
                     {
-                        ClearActor(_actor);
-                    }
+                        var ex = new PreRestartException(_self, e, cause, optionalMessage);
+                        Publish(new Error(ex, _self.Path.ToString(), failedActor.GetType(), e.Message));
+                    });
+                }
+                finally
+                {
+                    ClearActor(_actor);
                 }
 
                 global::System.Diagnostics.Debug.Assert(Mailbox.IsSuspended(), "Mailbox must be suspended during restart, status=" + Mailbox.CurrentStatus());

src/core/Akka/Util/Base64Encoding.cs

@@ -34,7 +34,7 @@ internal static string Base64Encode(this long value, string prefix)
         {
             // 11 is the number of characters it takes to represent long.MaxValue
             // so we will never need a larger size for encoding longs
-            Span<char> sb = stackalloc char[11 + prefix?.Length ?? 0];
+            Span<char> sb = stackalloc char[11 + (prefix?.Length ?? 0)];
             var spanIndex = 0;
             if (!string.IsNullOrWhiteSpace(prefix) && prefix.Length > 0)
             {

src/examples/HelloAkka/HelloWorld/GreetingActor.cs

@@ -5,8 +5,6 @@
 // </copyright>
 //-----------------------------------------------------------------------
 #region akka-hello-world-greeting
-
-using System;
 using Akka.Actor;
 
 namespace HelloWorld
@@ -19,11 +17,19 @@ public class GreetingActor : ReceiveActor
         public GreetingActor()
         {
             // Tell the actor to respond to the Greet message
-            Receive<Greet>(greet => Console.WriteLine($"Hello {greet.Who}", ConsoleColor.Green));
+            Receive<Greet>(greet => Console.WriteLine($"Hello {greet.Who}"));
+        }
+        protected override void PreStart()
+        {
+            Console.ForegroundColor = ConsoleColor.Green;
+            Console.WriteLine("Good Morning, we are awake!");
         }
-        protected override void PreStart() => Console.WriteLine("Good Morning, we are awake!", ConsoleColor.Green);
 
-        protected override void PostStop() => Console.WriteLine("Good Night, going to bed!", ConsoleColor.Red);
+        protected override void PostStop()
+        {
+            Console.ForegroundColor = ConsoleColor.Red;
+            Console.WriteLine("Good Night, going to bed!");
+        }
     }
 }
 #endregion