Render error messages in the container itself

fixes #6280

application/controllers/ErrorController.php

@@ -19,6 +19,7 @@ class ErrorController extends ActionController
     {
         $error      = $this->_getParam('error_handler');
         $exception  = $error->exception;
+        $this->getTabs()->showOnlyCloseButton();
 
         Logger::error($exception);
         Logger::error('Stacktrace: %s', $exception->getTraceAsString());

application/views/scripts/error/error.phtml

@@ -1,8 +1,9 @@
-<?php if ($this->title): ?>
 <div class="controls">
+<?= $this->tabs->render($this) ?>
+<?php if ($this->title): ?>
 <h1><?= $this->escape($title) ?></h1>
-</div>
 <?php endif ?>
+</div>
 <div class="content">
 <?php if ($this->message): ?>
   <p><strong><?= nl2br($this->escape($message)) ?></strong></p>

public/js/icinga/loader.js

@@ -594,18 +594,7 @@
         onFailure: function (req, textStatus, errorThrown) {
             var url = req.url;
 
-            if (req.status === 500) {
-                if (this.exception === null) {
-                    req.$target.addClass('impact');
-
-                    this.exception = this.createNotice(
-                        'error',
-                        $('h1', $(req.responseText)).first().html(),
-                        true
-                    );
-                    this.icinga.ui.fixControls();
-                }
-            } else if (req.status > 0) {
+            if (req.status > 0) {
                 this.icinga.logger.error(
                     req.status,
                     errorThrown + ':',
@@ -617,9 +606,6 @@
                     req.action,
                     req.autorefresh
                 );
-
-                // Header example:
-                // Icinga.debug(req.getResponseHeader('X-Icinga-Redirect'));
             } else {
                 if (errorThrown === 'abort') {
                     this.icinga.logger.debug(