fix type errors

src/timelines/MediaViewer.tsx

@@ -38,7 +38,7 @@ function clamp(input: number, min: number, max: number) {
 }
 
 const MediaViewer: ParentComponent<MediaViewerProps> = (props) => {
-  let rootRef: HTMLDialogElement;
+  let rootRef!: HTMLDialogElement;
 
   type State = {
     ref?: HTMLElement;

src/timelines/PullDownToRefresh.tsx

@@ -17,7 +17,7 @@ const PullDownToRefresh: Component<{
   linkedElement?: HTMLElement;
   onRefresh?: () => void;
 }> = (props) => {
-  let rootElement: HTMLDivElement;
+  let rootElement!: HTMLDivElement;
   const [pullDown, setPullDown] = createSignal(0);
 
   const stopPos = () => 160;

src/timelines/TootLangPicker.tsx

@@ -23,7 +23,7 @@ type ChooseTootLangProps = {
 };
 
 const ChooseTootLang: Component<ChooseTootLangProps> = (props) => {
-  let listRef: HTMLUListElement;
+  let listRef!: HTMLUListElement;
   const [t] = createTranslator(
     (code) =>
       import(`./i18n/${code}.json`) as Promise<{

src/timelines/toots/PreviewCard.tsx

@@ -17,7 +17,7 @@ export function PreviewCard(props: {
   src: mastodon.v1.PreviewCard;
   alwaysCompact?: boolean;
 }) {
-  let root: HTMLAnchorElement;
+  let root!: HTMLAnchorElement;
 
   createEffect(() => {
     if (props.alwaysCompact) {

src/timelines/toots/TootPoll.tsx

@@ -33,7 +33,7 @@ type TootPollProps = {
 };
 
 const TootPoll: Component<TootPollProps> = (props) => {
-  let list: HTMLUListElement;
+  let list!: HTMLUListElement;
   const { vote } = useTootEnv();
 
   const now = useTimeSource();