Ensured default domain redirects cannot be edited through regular approach

module/Core/src/Domain/DomainService.php

@@ -10,6 +10,7 @@ use Shlinkio\Shlink\Core\Domain\Model\DomainItem;
 use Shlinkio\Shlink\Core\Domain\Repository\DomainRepositoryInterface;
 use Shlinkio\Shlink\Core\Entity\Domain;
 use Shlinkio\Shlink\Core\Exception\DomainNotFoundException;
+use Shlinkio\Shlink\Core\Exception\InvalidDomainException;
 use Shlinkio\Shlink\Core\Options\NotFoundRedirectOptions;
 use Shlinkio\Shlink\Rest\ApiKey\Role;
 use Shlinkio\Shlink\Rest\Entity\ApiKey;
@@ -78,12 +79,17 @@ class DomainService implements DomainServiceInterface
 
     /**
      * @throws DomainNotFoundException
+     * @throws InvalidDomainException
      */
     public function configureNotFoundRedirects(
         string $authority,
         NotFoundRedirects $notFoundRedirects,
         ?ApiKey $apiKey = null
     ): Domain {
+        if ($authority === $this->defaultDomain) {
+            throw InvalidDomainException::forDefaultDomainRedirects();
+        }
+
         $domain = $this->getPersistedDomain($authority, $apiKey);
         $domain->configureNotFoundRedirects($notFoundRedirects);
 

module/Core/src/Domain/DomainServiceInterface.php

@@ -8,6 +8,7 @@ use Shlinkio\Shlink\Core\Config\NotFoundRedirects;
 use Shlinkio\Shlink\Core\Domain\Model\DomainItem;
 use Shlinkio\Shlink\Core\Entity\Domain;
 use Shlinkio\Shlink\Core\Exception\DomainNotFoundException;
+use Shlinkio\Shlink\Core\Exception\InvalidDomainException;
 use Shlinkio\Shlink\Rest\Entity\ApiKey;
 
 interface DomainServiceInterface
@@ -31,6 +32,7 @@ interface DomainServiceInterface
 
     /**
      * @throws DomainNotFoundException If the API key is restricted to one domain and a different one is provided
+     * @throws InvalidDomainException If default domain is provided
      */
     public function configureNotFoundRedirects(
         string $authority,

module/Core/src/Exception/InvalidDomainException.php

@@ -0,0 +1,33 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Shlinkio\Shlink\Core\Exception;
+
+use Fig\Http\Message\StatusCodeInterface;
+use Mezzio\ProblemDetails\Exception\CommonProblemDetailsExceptionTrait;
+use Mezzio\ProblemDetails\Exception\ProblemDetailsExceptionInterface;
+
+class InvalidDomainException extends DomainException implements ProblemDetailsExceptionInterface
+{
+    use CommonProblemDetailsExceptionTrait;
+
+    private const TITLE = 'Invalid domain';
+    private const TYPE = 'INVALID_DOMAIN';
+
+    private function __construct(string $message)
+    {
+        parent::__construct($message);
+    }
+
+    public static function forDefaultDomainRedirects(): self
+    {
+        $e = new self('You cannot configure default domain\'s redirects this way. Use the configuration or env vars.');
+        $e->detail = $e->getMessage();
+        $e->title = self::TITLE;
+        $e->type = self::TYPE;
+        $e->status = StatusCodeInterface::STATUS_BAD_REQUEST;
+
+        return $e;
+    }
+}