UX: do not show error title

app/assets/javascripts/discourse/models/post-stream.js.es6

@@ -767,14 +767,12 @@ const PostStream = RestModel.extend({
 
     // If the result was 404 the post is not found
     if (status === 404) {
-      topic.set('errorTitle', I18n.t('topic.not_found.title'));
       topic.set('notFoundHtml', result.jqXHR.responseText);
       return;
     }
 
     // If the result is 403 it means invalid access
     if (status === 403) {
-      topic.set('errorTitle', I18n.t('topic.invalid_access.title'));
       topic.set('noRetry', true);
       if (Discourse.User.current()) {
         topic.set('message', I18n.t('topic.invalid_access.description'));
@@ -785,7 +783,6 @@ const PostStream = RestModel.extend({
     }
 
     // Otherwise supply a generic error message
-    topic.set('errorTitle', I18n.t('topic.server_error.title'));
     topic.set('message', I18n.t('topic.server_error.description'));
   }
 

app/assets/javascripts/discourse/models/topic.js.es6

@@ -2,7 +2,6 @@ import RestModel from 'discourse/models/rest';
 
 const Topic = RestModel.extend({
   message: null,
-  errorTitle: null,
   errorLoading: false,
 
   fancyTitle: function() {

app/assets/javascripts/discourse/templates/components/header-extra-info.hbs

@@ -9,10 +9,6 @@
         {{#if topic.details.loaded}}
           {{topic-status topic=topic}}
           <a class='topic-link' href='{{unbound topic.url}}' {{action "jumpToTopPost"}}>{{{topic.fancyTitle}}}</a>
-        {{else}}
-          {{#if topic.errorLoading}}
-            <span class="error">{{topic.errorTitle}}</span>
-          {{/if}}
         {{/if}}
       </h1>
       {{#if topic.details.loaded}}