It doesn't make sense to redirect when not logged in on a non-GET

request. We should report a failure then. They likely logged out or
in another tab or timed out.

app/assets/javascripts/discourse/models/composer.js

@@ -524,10 +524,16 @@ Discourse.Composer = Discourse.Model.extend({
           postStream.undoPost(createdPost);
         }
         composer.set('composeState', OPEN);
+
         // TODO extract error handling code
         var parsedError;
         try {
-          parsedError = $.parseJSON(error.responseText).errors[0];
+          var parsedJSON = $.parseJSON(error.responseText);
+          if (parsedJSON.errors) {
+            parsedError = parsedJSON.errors[0];
+          } else if (parsedJSON.failed) {
+            parsedError = parsedJSON.message;
+          }
         }
         catch(ex) {
           parsedError = "Unknown error saving post, try again. Error: " + error.status + " " + error.statusText;

app/controllers/application_controller.rb

@@ -86,7 +86,13 @@ class ApplicationController < ActionController::Base
 
   rescue_from Discourse::NotLoggedIn do |e|
     raise e if Rails.env.test?
-    redirect_to "/"
+
+    if request.get?
+      redirect_to "/"
+    else
+      render status: 403, json: failed_json.merge(message: I18n.t(:not_logged_in))
+    end
+
   end
 
   rescue_from Discourse::NotFound do

config/locales/server.en.yml

@@ -33,6 +33,7 @@ en:
     backup_file_should_be_tar_gz: "The backup file should be a .tar.gz archive."
     not_enough_space_on_disk: "There is not enough space on disk to upload this backup."
 
+  not_logged_in: "You need to be logged in to do that."
   read_only_mode_enabled: "The site is in read only mode. Interactions are disabled."
 
   too_many_replies: