add flash messages and session_start

public/index.php

@@ -7,6 +7,7 @@ use App\Application\ResponseEmitter\ResponseEmitter;
 use DI\ContainerBuilder;
 use Slim\Factory\AppFactory;
 use Slim\Factory\ServerRequestCreatorFactory;
+use Slim\Flash\Messages;
 
 require __DIR__ . '/../vendor/autoload.php';
 
@@ -32,6 +33,8 @@ $repositories($containerBuilder);
 // Build PHP-DI Container instance
 $container = $containerBuilder->build();
 
+session_start();
+
 // Instantiate the app
 AppFactory::setContainer($container);
 $app = AppFactory::create();