chore: complete update

src/Framework/Config/Exceptions/RequiredEnvironmentVariableException.php

@@ -0,0 +1,17 @@
+<?php
+
+namespace App\Framework\Config\Exceptions;
+
+use App\Framework\Exception\FrameworkException;
+
+class RequiredEnvironmentVariableException extends FrameworkException
+{
+
+    /**
+     * @param string $key
+     */
+    public function __construct(string $key)
+    {
+        parent::__construct("Required environment variable '$key' is not set.");
+    }
+}