Make sure you have unsintalled any pre-existing Node.js installations before installing NVM. Mac: Use Homebrew to install NVM Windows: Download NVM from https://github.com/coreybutler/nvm-windows.
Once NVM is installed, open your preffered terminal and run the following to install Node.js 12.16.3:
nvm install 12.x
Then activate node 12.x
nvm use 12.x
yarn
yarn start
yarn start --static
yarn build
yarn build --static