Experimenting with a revised graphviz-viewer. Based on hpcc-systems/hpcc-js-wasm github 
graphviz-viewer
For some reason the .wasm files have to be at the same directory level as graphviz-viewer.js, so I just put everything there for now.
Created this roughly as follows:
npm install --save @hpcc-js/wasm find node_modules/@hpcc-js/wasm/dist -type f \ | xargs -I % cp % .