Fix tests

[mikedotexe]

Steps to reproduce:
cd frontend
yarn test
Note the error:

console.error node_modules/react-dom/cjs/react-dom.development.js:88
Warning: Can't perform a React state update on an unmounted component. This is a no-op, but it indicates a memory leak in your application. To fix, cancel all subscriptions and asynchronous tasks in the componentWillUnmount method.
in App (at App.test.js:6)

Also, there are other errors to address