[Moo] TypeError: el.parentNode is null when I try and wrap an element

[4fingers]

Hi,

I am trying to wrap a new element inside an element that has just been 
clicked but I am getting the following error in FF 17.0.1:
"TypeError: el.parentNode is null"

Here is an example of what I mean: http://jsfiddle.net/m92Lu/ 

Simply click on the "Click Me" text to get the error.

Any ideas on how I can resolve this issue?

Thanks