Hooks + multiple instances of React

# To people coming from search: please [read this page first](https://reactjs.org/warnings/invalid-hook-call-warning.html). It contains most common possible fixes! **Do you want to request a *feature* or report a *bug*?** Enhancement **What is the current behavior?** I had multiple instances of React by mistake. When trying to use hooks, got this error: `hooks can only be called inside the body of a function component` Which is not correct since I was using function components. Took me a while to find the real cause of the issue. **What is the expected behavior?** Show the correct error message. Maybe detect that the app has multiple instances of React and say that it may be the reason of bugs.