SubGraph : Cannot index into a null array

[mmt79]

I tired running the visualization command and I'm getting the following error:

▶ Plotting sub-graph for Azure Resource Group: "xxxx" 41.02s
SubGraph : Cannot index into a null array.
At C:\Users\Documents\WindowsPowerShell\Modules\AzViz\1.2.1\src\private\ConvertTo-DOTLangauge.ps1:78 char:39

• ... rkLayout += SubGraph -Name $VNetSubGraphName -Attributes $VNetSubGrap

Any pointers would be greatly appreciated