[Feature Request][eslint-plugin-react-hooks] no-ref-checks, display error when using useRef's return value as condition

https://github.com/reactjs/rfcs/issues/198 https://github.com/yannickcr/eslint-plugin-react/issues/3042 Not sure whether this belongs in `eslint-plugin-react-hooks` or `eslint-plugin-react`, but a contributor at the latter suggested this to be a more appropriate place. I've opened an issue instead of an RFC to discuss whether this is the appropriate place. https://github.com/yannickcr/eslint-plugin-react/issues/3042#issuecomment-899689312 I started migrating a codebase from class-based to function-based and came across some silliness. I had completely missed converting some of the ref checks: ```diff - const thing = this.thing; + const thing = useRef(props.thing); // I missed this - if (!thing) { + if (!thing.current) { ``` TypeScript considers `!useRef(props.thing)` to be perfectly valid since it may be testing for non-existence of the value even if it is not boolean. However, due to the rules of hooks, this value will never be undefined -- any checks for it are unnecessary and could either be an innocuous useless check or indicate a serious bug / typo. Thus, I'm thinking it might make sense to make sure a useRef's return value is never used as a boolean or condition at the react linter level. Not sure if it's possible with ESLint, but if so it could be a very useful rule which would catch a lot of bugs.