endless loop on code analysis with FxCop Introspection

Question

I'm trying to write a custom FxCop code analysis rule that will warn developers from methods containing too deeply nested code blocks, and will urge them to re-factor out the mess.

ex. I'm trying to avoid the following situation:

if(condition)
{
   foreach(var item in items)
   {
       if(anotherCondition)
       {
           for(var product in item.Products)
           {
               // even more nested statement blocks...
           }
       }
   }
}

I get a stackoverflow when I override the VisitBlock(Block block) method
that counts the block's depth, because apparently, there is a cyclic reference from one of the properties of the block to the block itself. i.e. the following is true for some i: block.Statements[i] == block

Why does such a cyclic reference exist? How to avoid it? Thanks!