Trying to Add an Legend using the legend.md API to my custom visualization

I am following  the installation instructions at the below link.  I am using the API 1.4.0 ... 

https://github.com/Microsoft/powerbi-visuals-utils-chartutils/blob/master/docs/usage/installation-guide.md

right after i start modifying the tsconfig.json and the pbviz.json ... the visualization in debug mode goes blank ... , but i can see still in the rows in the data view...  

Am I missing something ?