Explicitly provide undefined to useRef()

Author: wojtekmaj

packages/react-pdf/src/Document.tsx

@@ -271,8 +271,8 @@ const Document = forwardRef(function Document(
 
   const pages = useRef<HTMLDivElement[]>([]);
 
-  const prevFile = useRef<File>();
-  const prevOptions = useRef<Options>();
+  const prevFile = useRef<File | undefined>(undefined);
+  const prevOptions = useRef<Options | undefined>(undefined);
 
   useEffect(() => {
     if (file && file !== prevFile.current && isParameterObject(file)) {

packages/react-pdf/src/Page/TextLayer.tsx

@@ -40,7 +40,7 @@ export default function TextLayer() {
   const [textContentState, textContentDispatch] = useResolver<TextContent>();
   const { value: textContent, error: textContentError } = textContentState;
   const layerElement = useRef<HTMLDivElement>(null);
-  const endElement = useRef<HTMLElement>();
+  const endElement = useRef<HTMLElement | undefined>(undefined);
 
   warning(
     parseInt(

packages/react-pdf/src/shared/hooks/useCachedValue.ts

@@ -5,7 +5,7 @@ import { useRef } from 'react';
 import { isDefined } from '../utils.js';
 
 export default function useCachedValue<T>(getter: () => T): () => T {
-  const ref = useRef<T>();
+  const ref = useRef<T | undefined>(undefined);
 
   const currentValue = ref.current;