diff --git a/packages/php/email-editor/src/class-container.php b/packages/php/email-editor/src/class-container.php
index 9cbc833398..444488156f 100644
--- a/packages/php/email-editor/src/class-container.php
+++ b/packages/php/email-editor/src/class-container.php
@@ -1,29 +1,61 @@
-<?php declare(strict_types = 1);
+<?php
+/**
+ * This file is part of the MailPoet plugin.
+ *
+ * @package MailPoet\EmailEditor
+ */
 
+declare( strict_types = 1 );
 namespace MailPoet\EmailEditor;
 
+/**
+ * Class Container is a simple dependency injection container.
+ *
+ * @package MailPoet\EmailEditor
+ */
 class Container {
-	protected array $services  = array();
+	/**
+	 * A list of registered services
+	 *
+	 * @var array $services
+	 */
+	protected array $services = array();
+
+	/**
+	 * A list of created instances
+	 *
+	 * @var array
+	 */
 	protected array $instances = array();
 
-	public function set( string $name, callable $callable ): void {
-		$this->services[ $name ] = $callable;
+	/**
+	 * The method for registering a new service
+	 *
+	 * @param string   $name    The name of the service.
+	 * @param callable $callback The callable that will be used to create the service.
+	 * @return void
+	 */
+	public function set( string $name, callable $callback ): void {
+		$this->services[ $name ] = $callback;
 	}
 
 	/**
+	 * Method for getting a registered service
+	 *
 	 * @template T
-	 * @param class-string<T> $name
+	 * @param class-string<T> $name The name of the service.
 	 * @return T
+	 * @throws \Exception If the service is not found.
 	 */
-	public function get( string $name ) {
-		// Check if the service is already instantiated
+	public function get( $name ) {
+		// Check if the service is already instantiated.
 		if ( isset( $this->instances[ $name ] ) ) {
 			return $this->instances[ $name ];
 		}
 
-		// Check if the service is registered
+		// Check if the service is registered.
 		if ( ! isset( $this->services[ $name ] ) ) {
-			throw new \Exception( "Service not found: $name" );
+			throw new \Exception( esc_html( "Service not found: $name" ) );
 		}
 
 		$this->instances[ $name ] = $this->services[ $name ]( $this );