- remove not needed code

LightweightIocContainer/Exceptions/CircularDependencyException.cs

@@ -44,7 +44,7 @@ namespace LightweightIocContainer.Exceptions
             get
             {
                 StringBuilder message = new($"Circular dependency has been detected when trying to resolve `{ResolvingType}`.\n");
-                if (ResolveStack == null || !ResolveStack.Any())
+                if (!ResolveStack.Any())
                     return message.ToString();
 
                 message.Append("Resolve stack that resulted in the circular dependency:\n");

Test.LightweightIocContainer/IocContainerRecursionTest.cs

@@ -134,14 +134,6 @@ namespace Test.LightweightIocContainer
             Assert.AreEqual(message, exception.Message);
         }
 
-        [Test]
-        public void TestCircularDependencyExceptionNoStack()
-        {
-            CircularDependencyException circularDependencyException = new(typeof(IFoo), null);
-            string message = $"Circular dependency has been detected when trying to resolve `{typeof(IFoo)}`.\n";
-            Assert.AreEqual(message, circularDependencyException.Message);
-        }
-
         [Test]
         public void TestNonCircularDependencies()
         {