Naming state values and update functions

[matthewdking]

Mostly this is 👌 but just thought I would mention that in general the state value and update function are normally named as value and setValue.

You have this on most but for the error message I would just rename them to be consistent.

https://github.com/fac19/week10-Chlat/blob/09c57b167908cc102afeab5f075137a16abbfbe2/src/App.js#L15

const [errorMessage, setErrorMessage] = React.useState("");