locale fix

lighthouse-core/index.js

@@ -35,7 +35,7 @@ const Config = require('./config/config');
 async function lighthouse(url, flags, configJSON) {
   // TODO(bckenny): figure out Flags types.
   flags = flags || /** @type {LH.Flags} */ ({});
-  i18n.setLocale(flags.locale || 'en-US');
+  i18n.setLocale(flags.locale);
 
   // set logging preferences, assume quiet
   flags.logLevel = flags.logLevel || 'error';

lighthouse-core/lib/i18n.js

@@ -43,6 +43,10 @@ const formats = {
   },
 };
 
+/**
+ * @param {string} msg
+ * @param {Record<string, *>} values
+ */
 function preprocessMessageValues(msg, values) {
   const parsed = MessageParser.parse(msg);
   // Replace all the bytes with KB
@@ -71,7 +75,7 @@ module.exports = {
       // fallback to the original english message if we couldn't find a message in the specified locale
       // better to have an english message than no message at all, in some number cases it won't even matter
       const messageForMessageFormat = localeStrings[lookupKey] || msg
-      // when using accented english, force the use of a different locale for numbers
+      // when using accented english, force the use of a different locale for number formatting
       const localeForMessageFormat = locale === 'en-XA' ? 'de-DE' : locale;
 
       const formatter = new MessageFormat(
@@ -86,6 +90,7 @@ module.exports = {
   },
   /** @param {string} newLocale */
   setLocale(newLocale) {
+    if (typeof newLocale === 'undefined') return;
     locale = newLocale;
   },
 };