PLT-3958 Updated title for permalink error page (#5970)

webapp/actions/global_actions.jsx

@@ -211,7 +211,10 @@ export function emitPostFocusEvent(postId, onSuccess) {
                 link += 'town-square';
             }
 
-            browserHistory.push('/error?message=' + encodeURIComponent(Utils.localizeMessage('permalink.error.access', 'Permalink belongs to a deleted message or to a channel to which you do not have access.')) + '&link=' + encodeURIComponent(link));
+            const message = encodeURIComponent(Utils.localizeMessage('permalink.error.access', 'Permalink belongs to a deleted message or to a channel to which you do not have access.'));
+            const title = encodeURIComponent(Utils.localizeMessage('permalink.error.title', 'Message Not Found'));
+
+            browserHistory.push('/error?message=' + message + '&title=' + title + '&link=' + encodeURIComponent(link));
         }
     );
 }

webapp/i18n/en.json

@@ -1794,6 +1794,7 @@
   "pending_post_actions.cancel": "Cancel",
   "pending_post_actions.retry": "Retry",
   "permalink.error.access": "Permalink belongs to a deleted message or to a channel to which you do not have access.",
+  "permalink.error.title": "Message Not Found",
   "post_attachment.collapse": "Show less...",
   "post_attachment.more": "Show more...",
   "post_body.commentedOn": "Commented on {name}{apostrophe} message: ",