first commit

system/Exceptions/AlertError.php

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+<?php
+
+/**
+ * This file is part of CodeIgniter 4 framework.
+ *
+ * (c) CodeIgniter Foundation <admin@codeigniter.com>
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ */
+
+namespace CodeIgniter\Exceptions;
+
+use Error;
+
+/**
+ * Error: Action must be taken immediately (system/db down, etc)
+ */
+class AlertError extends Error
+{
+}