Prefix preferred system locales with l10n_util logic

app/locale.ts

@@ -55,8 +55,8 @@ export function load({
   preferredSystemLocales: Array<string>;
   logger: Pick<LoggerType, 'error' | 'warn' | 'info'>;
 }): LocaleType {
-  if (preferredSystemLocales.length === 0) {
+  if (preferredSystemLocales == null) {
-    throw new TypeError('`appLocale` is required');
+    throw new TypeError('`preferredSystemLocales` is required');
   }
 
   if (!logger || !logger.error) {
@@ -66,6 +66,10 @@ export function load({
     throw new TypeError('`logger.warn` is required');
   }
 
+  if (preferredSystemLocales.length === 0) {
+    logger.warn('`preferredSystemLocales` was empty');
+  }
+
   const english = getLocaleMessages('en');
 
   for (const locale of preferredSystemLocales) {

app/main.ts

@@ -1619,7 +1619,11 @@ ipc.on('database-error', (_event: Electron.Event, error: string) => {
 function loadPreferredSystemLocales(): Array<string> {
   return getEnvironment() === Environment.Test
     ? ['en']
-    : app.getPreferredSystemLanguages();
+    : [
+        // TODO(DESKTOP-4929): Temp fix to inherit Chromium's l10n_util logic
+        app.getLocale(),
+        ...app.getPreferredSystemLanguages(),
+      ];
 }
 
 async function getDefaultLoginItemSettings(): Promise<LoginItemSettingsOptions> {
@@ -1676,7 +1680,7 @@ app.on('ready', async () => {
     logger.info(
       `app.ready: preferred system locales: ${preferredSystemLocales.join(
         ', '
-      )}}`
+      )}`
     );
     resolvedTranslationsLocale = loadLocale({
       preferredSystemLocales,