Migrate to app router (#2254)

hooks/useUpdateEffect.ts

@@ -1,15 +0,0 @@
-import { useEffect } from "react";
-import useFirstMountState from "./useFirstMountState";
-
-// identical to `useEffect()` but ignores the first invocation
-const useUpdateEffect: typeof useEffect = (effect, deps) => {
-  const isFirstMount = useFirstMountState();
-
-  useEffect(() => {
-    if (!isFirstMount) {
-      return effect();
-    }
-  }, deps); // eslint-disable-line react-hooks/exhaustive-deps
-};
-
-export default useUpdateEffect;