Remove empty keys to allow English fallback

ui/src/i18nProvider/index.js

@@ -7,14 +7,27 @@ import en from './en.json'
 // Only returns current selected locale if its translations are found in localStorage
 const defaultLocale = function () {
   const locale = localStorage.getItem('locale')
-  const current = localStorage.getItem('translation')
+  const current = JSON.parse(localStorage.getItem('translation'))
   if (current && current.id === locale) {
     return locale
   }
   return 'en'
 }
 
+const removeEmpty = (obj) => {
+  for (let k in obj) {
+    if (obj.hasOwnProperty(k) && typeof obj[k] === 'object') {
+      removeEmpty(obj[k])
+    } else {
+      if (!obj[k]) {
+        delete obj[k]
+      }
+    }
+  }
+}
+
 const prepareLanguage = (lang) => {
+  removeEmpty(lang)
   // Make "albumSongs" resource use the same translations as "song"
   lang.resources.albumSong = lang.resources.song
   // ra.boolean.null should always be empty