D3 append is not a function when using with VueJS and Vuex

I have a html 'div' and I am trying to append another div to it by the following :

var myDiv = d3.select("#divId")

myDiv.append("div")

And I get the following error :

myDiv .append is not a function

Any ideas ?

I have put together a codepen that's similar to what I have : https://codepen.io/anon/pen/oMBGmd?editors=1010

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