New to react.js -- greyish black screen

[vfulco]

A noob to react.js,-- Install all dependencies using npm on Ubuntu 18.04. Reports 5 vulnerabilities, 1 requiring manual fixing, 3 updates for 4 vulnerabilities will break things. Change repo name to mine in default.config.js

Launch dev server using custom.config.js (my endpoints) and I get a blank black grey page and the serverless logo on my browser tab. TIA for any insights.

npm --version 6.5.0 node.js --version 8.15.0