diff --git a/src/bootstrap.php b/src/bootstrap.php
index 5646681..c9c9a1f 100644
--- a/src/bootstrap.php
+++ b/src/bootstrap.php
@@ -1,15 +1,15 @@
 <?php
 
-spl_autoload_register(callback: function($className) {
-    $prefix = 'App';
+spl_autoload_register(callback: function ($className) {
+    $prefix  = 'App';
     $baseDir = __DIR__;
 
-    $len = strlen(string: $prefix);
-    if (strncmp(string1: $prefix, string2: $className, length: $len) !== 0) {
-        return;
+    $prefixLen = strlen(string: $prefix);
+    if (strncmp(string1: $prefix, string2: $className, length: $prefixLen) !== 0) {
+        die("Invalid class: $className");
     }
-    $realClassName = substr(string: $className, offset: $len);
-    $classLocation = $baseDir . str_replace(search: '\\', replace: '/', subject: $realClassName) . '.php';
+    $realClassNamePSRpath = substr(string: $className, offset: $prefixLen);
+    $classLocation = $baseDir . str_replace(search: '\\', replace: '/', subject: $realClassNamePSRpath) . '.php';
     if (file_exists(filename: $classLocation)) {
         require $classLocation;
     } else {