contextInitial.js

function App() {
  const [currentUser, setCurrentUser] = React.useState(null);
  const [counter, setCounter] = React.useState(1);

  return (
    <SessionContext.Provider
      value={React.useMemo(() => ({ currentUser, setCurrentUser }), [
        currentUser,
        setCurrentUser,
      ])}
    >
      <CounterContext.Provider
        value={React.useMemo(() => ({ counter, setCounter }), [
          counter,
          setCounter,
        ])}
      >
        <SessionForm />
        <SessionCounterMessage />
        <CounterButtons />
      </CounterContext.Provider>
    </SessionContext.Provider>
  );
}