An error occurred during a call to extension function 'tagCloud'. See InnerException for a complete description of the error.; System.InvalidOperationException: Collection was modified; enumeration operation may not execute.
   at System.ThrowHelper.ThrowInvalidOperationException(ExceptionResource resource)
   at System.Collections.Generic.List`1.Enumerator.MoveNextRare()
   at Pixel.Core.Site.XsltExtension.tagCloud(String parentId)