Remove extra util file

It is not necessary.

src/confirmationModal.tsx

@@ -8,7 +8,7 @@ import {
   useImperativeHandle,
 } from "react";
 import { ModalProps, ModalHandle, Modal, Spinner, Button, boxError } from ".";
-import { currentRef } from "./utilFunc";
+import { currentRef } from "./util";
 
 
 type ConfirmationModalProps = Omit<ModalProps, "closable" | "title"> & {

src/index.tsx

@@ -11,7 +11,6 @@ export * from "./floating";
 export * from "./header";
 export * from "./spinner";
 export * from "./util";
-export * from "./utilFunc";
 export * from "./modal";
 export * from "./styledButton";
 

src/util.tsx

@@ -1,4 +1,5 @@
 import { MutableRefObject, useEffect } from "react";
+import { bug } from "./err";
 
 /**
  * A switch-case-like expression with exhaustiveness check (or fallback value).
@@ -69,3 +70,13 @@ export const useOnOutsideClick = (
     return () => document.removeEventListener("mousedown", handler);
   });
 };
+
+/**
+ * Accesses the current value of a ref, signaling an error when it is unbound.
+ * Note: **Don't** use this if you expect the ref to be unbound temporarily.
+ * This is mainly for accessing refs in event handlers for elements
+ * that are guaranteed to be alive as long as the ref itself.
+ */
+export const currentRef = <T, >(ref: React.RefObject<T>): T => (
+  ref.current ?? bug("ref unexpectedly unbound")
+);