[Glitch] Upgrade to typescript-eslint v6

Port a7253075d1 to glitch-soc

Signed-off-by: Claire <claire.github-309c@sitedethib.com>

app/javascript/flavours/glitch/locales/global_locale.ts

@@ -3,15 +3,19 @@ export interface LocaleData {
   messages: Record<string, string>;
 }
 
-let loadedLocale: LocaleData;
+let loadedLocale: LocaleData | undefined;
 
 export function setLocale(locale: LocaleData) {
   loadedLocale = locale;
 }
 
-export function getLocale() {
-  if (!loadedLocale && process.env.NODE_ENV === 'development') {
-    throw new Error('getLocale() called before any locale has been set');
+export function getLocale(): LocaleData {
+  if (!loadedLocale) {
+    if (process.env.NODE_ENV === 'development') {
+      throw new Error('getLocale() called before any locale has been set');
+    } else {
+      return { locale: 'unknown', messages: {} };
+    }
   }
 
   return loadedLocale;

app/javascript/flavours/glitch/locales/load_locale.ts

@@ -6,6 +6,7 @@ import { isLocaleLoaded, setLocale } from './global_locale';
 const localeLoadingSemaphore = new Semaphore(1);
 
 export async function loadLocale() {
+  // eslint-disable-next-line @typescript-eslint/prefer-nullish-coalescing -- we want to match empty strings
   const locale = document.querySelector<HTMLElement>('html')?.lang || 'en';
 
   // We use a Semaphore here so only one thing can try to load the locales at