Enable stricter Typescript options (#30435)

app/javascript/entrypoints/public.tsx

@@ -65,7 +65,7 @@ window.addEventListener('message', (e) => {
       {
         type: 'setHeight',
         id: data.id,
-        height: document.getElementsByTagName('html')[0].scrollHeight,
+        height: document.getElementsByTagName('html')[0]?.scrollHeight,
       },
       '*',
     );
@@ -135,7 +135,7 @@ function loaded() {
     );
   };
   const todayFormat = new IntlMessageFormat(
-    localeData['relative_format.today'] || 'Today at {time}',
+    localeData['relative_format.today'] ?? 'Today at {time}',
     locale,
   );
 
@@ -288,13 +288,13 @@ function loaded() {
       if (statusEl.dataset.spoiler === 'expanded') {
         statusEl.dataset.spoiler = 'folded';
         this.textContent = new IntlMessageFormat(
-          localeData['status.show_more'] || 'Show more',
+          localeData['status.show_more'] ?? 'Show more',
           locale,
         ).format() as string;
       } else {
         statusEl.dataset.spoiler = 'expanded';
         this.textContent = new IntlMessageFormat(
-          localeData['status.show_less'] || 'Show less',
+          localeData['status.show_less'] ?? 'Show less',
           locale,
         ).format() as string;
       }
@@ -316,8 +316,8 @@ function loaded() {
 
       const message =
         statusEl.dataset.spoiler === 'expanded'
-          ? localeData['status.show_less'] || 'Show less'
-          : localeData['status.show_more'] || 'Show more';
+          ? localeData['status.show_less'] ?? 'Show less'
+          : localeData['status.show_more'] ?? 'Show more';
       spoilerLink.textContent = new IntlMessageFormat(
         message,
         locale,

app/javascript/entrypoints/remote_interaction_helper.ts

@@ -67,7 +67,9 @@ const fetchInteractionURLFailure = () => {
   );
 };
 
-const isValidDomain = (value: string) => {
+const isValidDomain = (value: unknown) => {
+  if (typeof value !== 'string') return false;
+
   const url = new URL('https:///path');
   url.hostname = value;
   return url.hostname === value;
@@ -124,6 +126,11 @@ const fromAcct = (acct: string) => {
   const domain = segments[1];
   const fallbackTemplate = `https://${domain}/authorize_interaction?uri={uri}`;
 
+  if (!domain) {
+    fetchInteractionURLFailure();
+    return;
+  }
+
   axios
     .get(`https://${domain}/.well-known/webfinger`, {
       params: { resource: `acct:${acct}` },