quick'n'dirty state replacement that emulates the general behaviour of the old setState

useLegacyState.js

// hook to emulate legacy state behaviour
const useLegacyState = (initialState = {}) => {
  const [state, setState] = useState(initialState)

  function setLegacyState (partialNewState) {
    let newState = {...state}

    if (typeof partialNewState === 'object' && partialNewState !== null) {
      newState = {...newState, ...partialNewState}
    }

    setState(newState)
  }

  return [state, setLegacyState]
}