diff --git a/.phpstorm.meta.php b/.phpstorm.meta.php
new file mode 100644
index 0000000..2ed7926
--- /dev/null
+++ b/.phpstorm.meta.php
@@ -0,0 +1,8 @@
+<?php
+
+namespace PHPSTORM_META {
+    override(
+        \Psr\Container\ContainerInterface::get(0),
+        map(['@'])
+    );
+}
diff --git a/.psalm-stubs.meta.php b/.psalm-stubs.meta.php
new file mode 100644
index 0000000..bcc8757
--- /dev/null
+++ b/.psalm-stubs.meta.php
@@ -0,0 +1,17 @@
+<?php
+
+namespace Psr\Container {
+    interface ContainerInterface
+    {
+        /**
+         * @psalm-template T of object
+         * @psalm-param class-string<T>|string $id
+         * @return (
+         *      $id is class-string<T>
+         *      ? T
+         *      : mixed
+         * )
+         */
+        public function get(string $id): mixed;
+    }
+}
\ No newline at end of file
diff --git a/config/container.php b/config/container.php
index ec8cb42..117b945 100644
--- a/config/container.php
+++ b/config/container.php
@@ -6,7 +6,9 @@
 // Retrieve configuration
 $appConfig = require __DIR__ . '/application.config.php';
 if (file_exists(__DIR__ . '/development.config.php')) {
-    $appConfig = ArrayUtils::merge($appConfig, require __DIR__ . '/development.config.php');
+    /** @var array $devConfig */
+    $devConfig = require __DIR__ . '/development.config.php';
+    $appConfig = ArrayUtils::merge($appConfig, $devConfig);
 }
 
 return Application::init($appConfig)
diff --git a/module/Application/test/ModuleTest.php b/module/Application/test/ModuleTest.php
new file mode 100644
index 0000000..d4368d6
--- /dev/null
+++ b/module/Application/test/ModuleTest.php
@@ -0,0 +1,23 @@
+<?php
+
+declare(strict_types=1);
+
+namespace ApplicationTest;
+
+use Application\Module;
+use PHPUnit\Framework\TestCase;
+
+/**
+ * @covers \Application\Module;
+ */
+class ModuleTest extends TestCase
+{
+    public function testProvidesConfig(): void
+    {
+        $module = new Module();
+        $config = $module->getConfig();
+
+        self::assertArrayHasKey('router', $config);
+        self::assertArrayHasKey('controllers', $config);
+    }
+}
diff --git a/psalm.xml b/psalm.xml
index dec1ac3..c9e2e08 100644
--- a/psalm.xml
+++ b/psalm.xml
@@ -37,6 +37,10 @@
         </InternalMethod>
     </issueHandlers>
 
+    <stubs>
+        <file name=".psalm-stubs.meta.php"/>
+    </stubs>
+
     <plugins>
         <pluginClass class="Psalm\PhpUnitPlugin\Plugin"/>
     </plugins>
diff --git a/public/index.php b/public/index.php
index d5bb012..6bd404c 100644
--- a/public/index.php
+++ b/public/index.php
@@ -12,7 +12,7 @@
 
 // Decline static file requests back to the PHP built-in webserver
 if (php_sapi_name() === 'cli-server') {
-    $path = realpath(__DIR__ . parse_url($_SERVER['REQUEST_URI'], PHP_URL_PATH));
+    $path = realpath(__DIR__ . parse_url($_SERVER['REQUEST_URI'] ?? '', PHP_URL_PATH));
     if (is_string($path) && __FILE__ !== $path && is_file($path)) {
         return false;
     }
@@ -32,5 +32,6 @@
 
 $container = require __DIR__ . '/../config/container.php';
 // Run the application!
-$container->get('Application')
-    ->run();
+/** @var Application $app */
+$app = $container->get('Application');
+$app->run();