Can create circular reference by adding first block to second block's folder

Description

Tested on cms.ui 10.8.0 but most likely this issue appears in any version that has a "For this block".

Steps to reproduce

1. Create a block called "block1".
2. Publish it.
3. Add the block to any page's contentarea.
4. Create another block, called "block2", inside block1's "For this block" folder and publish it.
5. Edit block2.
6. Move block1 inside block2's folder "For this block".

Actual: Causes errors. And, if the block is in a contentarea of a page, it causes the page not to load.
Also, the many error messages seem to cause a performance issue.

The following stacktrace will emerge:

ERROR EPiServer.Global: 1.2.5 Unhandled exception in ASP.NET
System.InvalidOperationException: Failed to Get because of circular references
at EPiServer.Core.Internal.DefaultContentLanguageSettingsHandler.ValidateCircularReference(ContentReference contentLink, HashSet`1 visitedContents)
at EPiServer.Core.Internal.DefaultContentLanguageSettingsHandler.Get(ContentReference contentLink, HashSet`1 visitedContents)
at EPiServer.Core.Internal.DefaultContentLanguageSettingsHandler.GetSetting(ContentReference contentLink, HashSet`1 visitedContents)
at System.Collections.Concurrent.ConcurrentDictionary`2.GetOrAdd(TKey key, Func`2 valueFactory)
at EPiServer.Core.Internal.DefaultContentLanguageSettingsHandler.GetSetting(ContentReference contentLink, HashSet`1 visitedContents)
at System.Collections.Concurrent.ConcurrentDictionary`2.GetOrAdd(TKey key, Func`2 valueFactory)
at EPiServer.Core.Internal.DefaultContentLanguageSettingsHandler.GetSetting(ContentReference contentLink, HashSet`1 visitedContents)
at System.Collections.Concurrent.ConcurrentDictionary`2.GetOrAdd(TKey key, Func`2 valueFactory)
at EPiServer.Core.Internal.DefaultContentLanguageSettingsHandler.GetSetting(ContentReference contentLink, HashSet`1 visitedContents)
at System.Collections.Concurrent.ConcurrentDictionary`2.GetOrAdd(TKey key, Func`2 valueFactory)
at EPiServer.Core.Internal.DefaultContentLanguageSettingsHandler.GetSetting(ContentReference contentLink, HashSet`1 visitedContents)
at System.Collections.Concurrent.ConcurrentDictionary`2.GetOrAdd(TKey key, Func`2 valueFactory)
at EPiServer.Core.Internal.DefaultContentLanguageSettingsHandler.Get(ContentReference contentLink)
at EPiServer.Core.Internal.DefaultContentLanguageSettingsHandler.Get(ContentReference contentLink, String languageBranch)
at EPiServer.Core.Internal.LanguagePipeline.Pipe(ContentReference contentLink, IContent contentInstance, LoaderOptions loaderOptions, Func`3 loadingDelegate)
at EPiServer.Core.Internal.ProviderPipelineImplementation.GetItem(ContentProvider provider, ContentReference contentLink, LoaderOptions loaderOptions)
at EPiServer.Core.Internal.DefaultContentLoader.TryGet[T](ContentReference contentLink, LoaderOptions loaderOptions, T& content)
at EPiServer.Cms.Shell.UI.Rest.Internal.ContentStore.GetContent(ContentReference contentReference, DefaultQueryParameters queryParameters)
at EPiServer.Cms.Shell.UI.Rest.Internal.ContentStore.Get(ContentReference id, String query, ContentReference referenceId, ContentReference[] references, String[] typeIdentifiers, Nullable`1 allLanguages, IEnumerable`1 sortColumns, ItemRange range)
at lambda_method(Closure , ControllerBase , Object[] )
at System.Web.Mvc.ReflectedActionDescriptor.Execute(ControllerContext controllerContext, IDictionary`2 parameters)
at System.Web.Mvc.ControllerActionInvoker.InvokeActionMethod(ControllerContext controllerContext, ActionDescriptor actionDescriptor, IDictionary`2 parameters)
at System.Web.Mvc.Async.AsyncControllerActionInvoker.<BeginInvokeSynchronousActionMethod>b__39(IAsyncResult asyncResult, ActionInvocation innerInvokeState)
at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncResult`2.CallEndDelegate(IAsyncResult asyncResult)
at System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeActionMethod(IAsyncResult asyncResult)
at System.Web.Mvc.Async.AsyncControllerActionInvoker.AsyncInvocationWithFilters.<InvokeActionMethodFilterAsynchronouslyRecursive>b__3d()
at System.Web.Mvc.Async.AsyncControllerActionInvoker.AsyncInvocationWithFilters.<>c_DisplayClass46.<InvokeActionMethodFilterAsynchronouslyRecursive>b_3f()
at System.Web.Mvc.Async.AsyncControllerActionInvoker.AsyncInvocationWithFilters.<>c_DisplayClass46.<InvokeActionMethodFilterAsynchronouslyRecursive>b_3f()
at System.Web.Mvc.Async.AsyncControllerActionInvoker.AsyncInvocationWithFilters.<>c_DisplayClass46.<InvokeActionMethodFilterAsynchronouslyRecursive>b_3f()
at System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeActionMethodWithFilters(IAsyncResult asyncResult)
at System.Web.Mvc.Async.AsyncControllerActionInvoker.<>c_DisplayClass21.<>cDisplayClass2b.<BeginInvokeAction>b_1c()
at System.Web.Mvc.Async.AsyncControllerActionInvoker.<>c_DisplayClass21.<BeginInvokeAction>b_1e(IAsyncResult asyncResult)
at System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeAction(IAsyncResult asyncResult)
at EPiServer.Shell.Services.Rest.RestControllerBase.EndExecute(IAsyncResult asyncResult)
at System.Web.HttpApplication.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()
at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)
System.InvalidOperationException: Failed to Get because of circular references
at EPiServer.Core.Internal.DefaultContentLanguageSettingsHandler.ValidateCircularReference(ContentReference contentLink, HashSet`1 visitedContents)
at EPiServer.Core.Internal.DefaultContentLanguageSettingsHandler.Get(ContentReference contentLink, HashSet`1 visitedContents)
at EPiServer.Core.Internal.DefaultContentLanguageSettingsHandler.GetSetting(ContentReference contentLink, HashSet`1 visitedContents)
at System.Collections.Concurrent.ConcurrentDictionary`2.GetOrAdd(TKey key, Func`2 valueFactory)
at EPiServer.Core.Internal.DefaultContentLanguageSettingsHandler.GetSetting(ContentReference contentLink, HashSet`1 visitedContents)
at System.Collections.Concurrent.ConcurrentDictionary`2.GetOrAdd(TKey key, Func`2 valueFactory)
at EPiServer.Core.Internal.DefaultContentLanguageSettingsHandler.GetSetting(ContentReference contentLink, HashSet`1 visitedContents)
at System.Collections.Concurrent.ConcurrentDictionary`2.GetOrAdd(TKey key, Func`2 valueFactory)
at EPiServer.Core.Internal.DefaultContentLanguageSettingsHandler.GetSetting(ContentReference contentLink, HashSet`1 visitedContents)
at System.Collections.Concurrent.ConcurrentDictionary`2.GetOrAdd(TKey key, Func`2 valueFactory)
at EPiServer.Core.Internal.DefaultContentLanguageSettingsHandler.GetSetting(ContentReference contentLink, HashSet`1 visitedContents)
at System.Collections.Concurrent.ConcurrentDictionary`2.GetOrAdd(TKey key, Func`2 valueFactory)
at EPiServer.Core.Internal.DefaultContentLanguageSettingsHandler.Get(ContentReference contentLink)
at EPiServer.Core.Internal.DefaultContentLanguageSettingsHandler.Get(ContentReference contentLink, String languageBranch)
at EPiServer.Core.Internal.LanguagePipeline.Pipe(ContentReference contentLink, IContent contentInstance, LoaderOptions loaderOptions, Func`3 loadingDelegate)
at EPiServer.Core.Internal.ProviderPipelineImplementation.GetItem(ContentProvider provider, ContentReference contentLink, LoaderOptions loaderOptions)
at EPiServer.Core.Internal.DefaultContentLoader.TryGet[T](ContentReference contentLink, LoaderOptions loaderOptions, T& content)
at EPiServer.Cms.Shell.UI.Rest.Internal.ContentStore.GetContent(ContentReference contentReference, DefaultQueryParameters queryParameters)
at EPiServer.Cms.Shell.UI.Rest.Internal.ContentStore.Get(ContentReference id, String query, ContentReference referenceId, ContentReference[] references, String[] typeIdentifiers, Nullable`1 allLanguages, IEnumerable`1 sortColumns, ItemRange range)
at lambda_method(Closure , ControllerBase , Object[] )
at System.Web.Mvc.ReflectedActionDescriptor.Execute(ControllerContext controllerContext, IDictionary`2 parameters)
at System.Web.Mvc.ControllerActionInvoker.InvokeActionMethod(ControllerContext controllerContext, ActionDescriptor actionDescriptor, IDictionary`2 parameters)
at System.Web.Mvc.Async.AsyncControllerActionInvoker.<BeginInvokeSynchronousActionMethod>b__39(IAsyncResult asyncResult, ActionInvocation innerInvokeState)
at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncResult`2.CallEndDelegate(IAsyncResult asyncResult)
at System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeActionMethod(IAsyncResult asyncResult)
at System.Web.Mvc.Async.AsyncControllerActionInvoker.AsyncInvocationWithFilters.<InvokeActionMethodFilterAsynchronouslyRecursive>b__3d()
at System.Web.Mvc.Async.AsyncControllerActionInvoker.AsyncInvocationWithFilters.<>c_DisplayClass46.<InvokeActionMethodFilterAsynchronouslyRecursive>b_3f()
at System.Web.Mvc.Async.AsyncControllerActionInvoker.AsyncInvocationWithFilters.<>c_DisplayClass46.<InvokeActionMethodFilterAsynchronouslyRecursive>b_3f()
at System.Web.Mvc.Async.AsyncControllerActionInvoker.AsyncInvocationWithFilters.<>c_DisplayClass46.<InvokeActionMethodFilterAsynchronouslyRecursive>b_3f()
at System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeActionMethodWithFilters(IAsyncResult asyncResult)
at System.Web.Mvc.Async.AsyncControllerActionInvoker.<>c_DisplayClass21.<>cDisplayClass2b.<BeginInvokeAction>b_1c()
at System.Web.Mvc.Async.AsyncControllerActionInvoker.<>c_DisplayClass21.<BeginInvokeAction>b_1e(IAsyncResult asyncResult)
at System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeAction(IAsyncResult asyncResult)
at EPiServer.Shell.Services.Rest.RestControllerBase.EndExecute(IAsyncResult asyncResult)
at System.Web.HttpApplication.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()
at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)