fix i18n

packages/app/src/server/routes/login.js

@@ -143,14 +143,14 @@ module.exports = function(crowi, app) {
     User.isRegisterable(email, username, (isRegisterable, errOn) => {
       const errors = [];
       if (!User.isEmailValid(email)) {
-        errors.push('email_address_could_not_be_used');
+        errors.push('message.email_address_could_not_be_used');
       }
       if (!isRegisterable) {
         if (!errOn.username) {
-          errors.push('user_id_is_not_available');
+          errors.push('message.user_id_is_not_available');
         }
         if (!errOn.email) {
-          errors.push('email_address_is_already_registered');
+          errors.push('message.email_address_is_already_registered');
         }
       }
       if (errors.length > 0) {