Throwing CustomUserMessageAuthenticationException in make:auth login

src/Maker/MakeAuthenticator.php

@@ -21,6 +21,7 @@
 use Symfony\Bundle\MakerBundle\Security\InteractiveSecurityHelper;
 use Symfony\Bundle\MakerBundle\Security\SecurityConfigUpdater;
 use Symfony\Bundle\MakerBundle\Security\SecurityControllerBuilder;
+use Symfony\Bundle\MakerBundle\Str;
 use Symfony\Bundle\MakerBundle\Util\ClassSourceManipulator;
 use Symfony\Bundle\MakerBundle\Util\YamlManipulationFailedException;
 use Symfony\Bundle\MakerBundle\Util\YamlSourceManipulator;
@@ -237,6 +238,7 @@ private function generateAuthenticatorClass(array $securityData, string $authent
                 'user_fully_qualified_class_name' => trim($userClassNameDetails->getFullName(), '\\'),
                 'user_class_name' => $userClassNameDetails->getShortName(),
                 'username_field' => $userNameField,
+                'username_field_label' => Str::asHumanWords($userNameField),
                 'user_needs_encoder' => $this->userClassHasEncoder($securityData, $userClass),
                 'user_is_entity' => $this->doctrineHelper->isClassAMappedEntity($userClass),
             ]
@@ -281,7 +283,7 @@ private function generateFormLoginFiles(string $controllerClass, string $userNam
             [
                 'username_field' => $userNameField,
                 'username_is_email' => false !== stripos($userNameField, 'email'),
-                'username_label' => ucfirst(implode(' ', preg_split('/(?=[A-Z])/', $userNameField))),
+                'username_label' => ucfirst(Str::asHumanWords($userNameField)),
             ]
         );
     }

src/Resources/skeleton/authenticator/LoginFormAuthenticator.tpl.php

@@ -8,6 +8,7 @@
 use Symfony\Component\HttpFoundation\Request;
 use Symfony\Component\Routing\RouterInterface;
 use Symfony\Component\Security\Core\Authentication\Token\TokenInterface;
+use Symfony\Component\Security\Core\Exception\CustomUserMessageAuthenticationException;
 <?= $user_needs_encoder ? "use Symfony\\Component\\Security\\Core\\Encoder\\UserPasswordEncoderInterface;\n" : null ?>
 use Symfony\Component\Security\Core\Exception\InvalidCsrfTokenException;
 use Symfony\Component\Security\Core\Security;
@@ -63,10 +64,17 @@ public function getUser($credentials, UserProviderInterface $userProvider)
             throw new InvalidCsrfTokenException();
         }
 
-        <?= $user_is_entity ? "return \$this->entityManager->getRepository($user_class_name::class)->findOneBy(['$username_field' => \$credentials['$username_field']]);\n"
+        <?= $user_is_entity ? "\$user = \$this->entityManager->getRepository($user_class_name::class)->findOneBy(['$username_field' => \$credentials['$username_field']]);\n"
         : "// Load / create our user however you need.
         // You can do this by calling the user provider, or with custom logic here.
-        return \$userProvider->loadUserByUsername(\$credentials['$username_field']);\n"; ?>
+        \$user = \$userProvider->loadUserByUsername(\$credentials['$username_field']);\n"; ?>
+
+        if (!$user) {
+            // fail authentication with a custom error
+            throw new CustomUserMessageAuthenticationException('<?= ucfirst($username_field_label) ?> could not be found.');
+        }
+
+        return $user;
     }
 
     public function checkCredentials($credentials, UserInterface $user)

src/Str.php

@@ -205,4 +205,9 @@ public static function areClassesAlphabetical(string $class1, string $class2)
 
         return $arr1[0] == $arr2[0];
     }
+
+    public static function asHumanWords(string $variableName): string
+    {
+        return implode(' ', preg_split('/(?=[A-Z])/', $variableName));
+    }
 }